Consulting AI for Murder | "Case by Case" | "48 Hours" Podcast

0:06 What began as a missing person's case

0:10 ended with the discovery of a monstrous crime.

0:14 Our community has been left heartbroken

0:17 and the victim's families shattered after this tragic loss.

0:22 That was Hillsboro County Sheriff Chad Kronister speaking about

0:25 the alleged murders of Nahita Bristie and J Lemon.

0:29 The two were doctoral students from Bangladesh studying at the University

0:33 of South Florida before they went missing last month.

0:37 Lemon's remains were found on a bridge over Tampa Bay on April 24th.

0:42 Rristie's remains were recovered 2 days later in the waterways in Tampa Bay.

0:47 Her remains were just identified last Friday.

0:50 Lemon's roommate, Hisham Abu Garby, he's a US-born citizen,

0:54 is facing two counts of murder in the first degree with a weapon.

0:59 He is also facing a litany of other charges.

1:01 Battery, tampering with physical evidence,

1:04 failure to report death to law enforcement,

1:07 false imprisonment, and unlawfully holding or moving

1:10 a dead human body in unapproved conditions.

1:14 And there's a twist that has added to growing concerns about AI and crime.

1:20 Now, according to prosecutors,

1:21 Abu Garve planned the murder with the help of Chat GPT.

1:27 He allegedly asked the AI software several questions

1:30 in the days leading up to the students disappearance,

1:33 like what happens if a human is put in a black garbage bag

1:37 and thrown in a dumpster and are cars checked at the Hillsbor River State Park?

1:43 Abu Garve is being represented by a public defender.

1:46 He is currently being held without bond.

1:49 This is 48 Hours case by case where each week the team from 48

1:54 Hours will bring you the biggest stories in true crime in real time.

1:58 I'm Natalie Morales.

2:00 Now with me to unpack it all is Miami Bay CBS News correspondent Cristian

2:04 Benavid who has been reporting on the story

2:07 since the two students first went missing.

2:10 Welcome Cristiana.

2:11 And this one is probably one

2:13 of the most horrific stories I've heard most recently.

2:16 Yeah, it has been a really troubling case.

2:18 Uh, thank you for having me.

2:19 Covering this story has been a whirlwind

2:21 that has shaken the University of South Florida,

2:23 which we'll just call USF from now on.

2:26 There's a lot to unpack.

2:28 There certainly is.

2:29 And before we get into the state's timeline

2:31 of events and the AI part of this as well,

2:35 what can you tell us about these two victims, Risty and Lemon,

2:39 we know they were very bright doctoral candidates there at USF, right?

2:44 Yeah, they were.

2:46 I mean, Natalie, I think it's important to take

2:47 a step back and look at their relationship.

2:50 Family members shared with us that the two had previously dated.

2:53 Throughout my reporting, I've been fortunate to speak with family

2:56 members and close friends of the two victims,

2:59 and they both were seen as hardworking

3:01 students who were dedicated to their families, communities, and education.

3:05 Bristie was a 27-year-old PhD candidate studying chemical engineering.

3:10 Lemon was also a 27-year-old PhD candidate.

3:14 He was studying the use of AI in environmental science

3:17 and was said to present his doctoral thesis shortly after he disappeared.

3:22 Yeah.

3:22 You know, I was watching footage from a vigil.

3:25 It was held in their honor last Friday.

3:27 And I noticed just how moved all who were there seemed to be by this loss.

3:32 When were the two though first reported to be missing?

3:36 So, according to court documents, on April 17th,

3:38 the USF Police Department was first notified

3:42 by a friend Omar Hosin that Brristie was missing.

3:46 According to the court filings, Hosine told USFPD that he had tried to get

3:52 a hold of Brristie and was not getting a response.

3:55 Hosine told me this was not typical behavior for Brristie,

3:59 that she always checked in with people within

4:01 her friend group and so he grew concerned.

4:05 Uh that same day that he reported Brristie missing,

4:08 Hosine visited Lemon's apartment and couldn't find him either.

4:14 Cristian, initially I know that there

4:15 were some rumors surrounding their disappearance.

4:18 I think it was during the press conference last week,

4:20 the sheriff said that the unproven rumor was

4:22 that the two were part of an arranged marriage,

4:25 that perhaps they ran away instead.

4:27 What can you tell us about that?

4:29 Right.

4:29 Exactly.

4:30 Uh this was something that initially circulated.

4:33 As we mentioned, according to the family, the two had dated.

4:36 Bristy's brother told me that at some

4:38 point that relationship had come to an end.

4:41 So, to him, it just didn't make sense

4:43 why the two would run away together at all.

4:47 Yeah.

4:47 No cause for disappearing off the grid.

4:51 So, when we look at the scope of this investigation,

4:55 when did it really start and and what was Abu Garvey's connection?

4:59 And I know you said he was a roommate of Lemon,

5:02 but what more can you tell us about what was going on between those two?

5:07 Well, look, detectives interviewed both of Lemon's two roommates.

5:11 According to prosecutors, one of his roommates was cooperative.

5:14 The other, Abu Garvey, who we know now has been charged with the murders,

5:19 was elusive, according to the sheriff.

5:21 Abu Garvey denied having any knowledge of Lemon or Brristie's whereabouts.

5:26 One of the first things investigators noticed about him, however,

5:28 was a wrapped cut that he had on his pinky.

5:31 And he claimed it was from cutting onions,

5:34 but they asked them what what is it specifically that he

5:38 had been cooking that day and he could not recall.

5:41 And so that raised suspicion.

5:44 Yeah, they're always looking for signs.

5:46 How were the disappearances of the two students then connected to Abu Garvey,

5:51 right?

5:51 Well, detectives had to do some digging at this point.

5:54 Uh, according to the court document, they really started with his car.

5:58 During his initial interview,

5:59 Abu Garvey confirmed that he drove a white Hyundai Genesis G80.

6:05 Detectives ran his tags and tracked his movements on April 16th.

6:09 That's the last day that Lemon and Burst were seen alive.

6:12 And according to prosecutors,

6:13 his car was seen driving westward towards Clearwater.

6:18 And just so our listeners know, Clearwater is a city.

6:20 It's about 30 minutes across Tampa Bay.

6:23 Not too far, but it's a drive.

6:26 Yeah, it is a drive.

6:27 Uh, but it's a straight shot across a long bridge

6:30 that cuts right over the water and it's over 9 mi long.

6:34 According to prosecutors,

6:35 Abu Garvey's vehicle was traveling westbound on the bridge

6:40 within 10 minutes of a ping to Lemon's phone.

6:46 Cristian, let's listen a little bit more to Sheriff Chad

6:49 Cronnister speaking at a press conference last Friday and he

6:52 talks about an early visit that they made to Leone's

6:56 apartment where they discovered key details that then elevated the case.

7:01 We go out there uh dumpster diving.

7:05 These detectives getting inside of the dumpster and empty

7:09 the entire contents and they find Zil's glasses,

7:14 his student ID, his wallet, and his clothes,

7:19 which are extremely bloodied at the time.

7:22 Again, this is where we get our first break.

7:24 This is where during this timeline,

7:27 this missing person's becomes a missing person endangered case.

7:32 Now, I've reported on many murder cases that started as a missing person case,

7:37 but when you see bloody items from this person in a dumpster,

7:42 I mean, those kinds of discoveries, they are not a positive sign, right?

7:46 At the very least, they give investigators some pause.

7:50 Yeah.

7:50 And so they go back then for a second interview with Abu Garvey.

7:54 What happened then?

7:56 Police said they asked Abu Garvey specifically about the 16th.

8:00 He initially claimed that Lemon and Briststeed had not been in his vehicle.

8:04 He also claimed that he hadn't gone to Clearwater.

8:07 When asked why he went to Clear Water,

8:10 he said he went looking for fishing spots.

8:12 It's at this point that investigators confronted him about Leon's

8:16 phone also showing up in the same area in Clear Water.

8:20 According to police, that's when Apple Garvey alters his story.

8:25 According to prosecutors,

8:27 he told investigators he was approached by Lemon

8:30 and asked to be driven there with his girlfriend Brishi.

8:33 Abu Garvey did not provide a reason why.

8:35 He said he dropped him off and left.

8:38 That contradicts what he said in the first interview.

8:41 Based on the circumstances, the evidence, and the interviews conducted,

8:45 probable cause was established to obtain search

8:47 warrants for Leon and Abu Garvey's shared apartment,

8:51 plus photos of Abu Garvey along with his car and phone.

8:55 And we do have a bit of the sheriff here now talking about the physical

8:59 evidence that officers also discovered when they

9:03 then returned to the apartment with that warrant.

9:05 They go into the residence and we have some amazing technology,

9:10 one of it being Blue Star that identifies the the presence of blood.

9:15 And when they deploy Blueest Star,

9:17 they can see in the kitchen area there's a large pool of blood.

9:22 They see that the blood continues down

9:24 the hallway and into our suspect's bedroom.

9:27 The technology is so precise and finite that we

9:32 can see the outline of a human being

9:35 on the floor next to our suspect's bed

9:37 where he was curled up in a fetal position.

9:40 So Christian, this technology, I mean, how does this actually work?

9:45 Right.

9:45 It it's really really interesting.

9:47 According to Blueest Star Forensics website,

9:49 when sprayed onto a suspected blood stain,

9:53 Blue Star immediately reacts to the iron present in red blood cells,

9:59 generating an intense blue light that you can see in the dark.

10:03 It's very much sort of like what you see in the movies, right,

10:07 when they're spraying something and then you see the blue light

10:10 light up on CSI or whatever show you may be watching.

10:14 So now prosecutors allege Abu Garvey got

10:18 a delivery to the sheriff department on the 16th.

10:21 What do we know about what was in that delivery?

10:24 That's right.

10:25 The documents allege Abu Garvey ordered trash bags, Lysol, funions,

10:30 and other items via Door Dash from CVS the day of their disappearances.

10:35 Plus, on April 11th, days before the two went missing,

10:38 court filings say Abu Garvey placed an order for fire starter,

10:42 charcoal, trash bags, and lighter fuel.

10:45 So, he was making all of these purchases even prior to them going missing.

10:51 This now moves quickly to an arrest.

10:54 The arrest itself, as I understand, was pretty dramatic.

10:57 How did it go down?

10:59 Right.

10:59 Yeah, really dramatic images.

11:01 So, the day after law enforcement obtains the search warrants,

11:04 officials respond to a 911 call about

11:06 a domestic issue at Abu Garvey's family home.

11:10 To be clear, this is different than the shared

11:15 apartment that he had with Lemon and another roommate.

11:18 So, this is the family home now.

11:20 And according to the arrest report,

11:22 Abu Garvey's younger sister confronted him after she found him in the living

11:26 room playing video games wearing only

11:29 a towel after a confrontation between the two.

11:32 Another family member called police.

11:34 And just to give you a sense, Natalie, this family was startled.

11:38 We have spoken to family members and it it it is

11:41 not like he is going there um on a regular basis.

11:46 So, it was really strange for him to suddenly show up out of nowhere.

11:51 Uh, in addition to that, the fact

11:53 that he wasn't wearing any clothes, only a towel,

11:55 and he's suddenly playing video games in the living

11:58 room was just a really odd situation for the family.

12:02 So, then walk me through what happened next when

12:05 police show up at the Abu Garvey family home.

12:08 SWAT approaches the building.

12:10 They shut down the entrance and exit to the whole neighborhood.

12:14 Abu Garvey, according to authorities,

12:15 barricades himself inside the house before eventually coming

12:19 out with his hands up wearing just that towel.

12:22 Uh he turns himself over at that point without incident.

12:27 There's no sort of violence that plays out.

12:29 They're able to take him into custody immediately.

12:32 So he's arrested on the spot.

12:34 However, they still don't know really what

12:37 happened yet to the two missing USF students.

12:41 They don't have the bodies at this point.

12:42 Right.

12:43 Right.

12:44 I mean, they have an idea that something happened in the shared apartment.

12:47 Right.

12:48 I remember initially police would not say whether the person

12:50 in custody was considered a suspect in the disappearance,

12:54 only that they are connected to the disappearance.

12:57 It wasn't until a few hours later that they

12:59 announced that Lemon's body had been discovered the same morning.

13:03 And according to prosecutors,

13:04 his body was found on another bridge that goes over the bay.

13:08 That's when they formally connected both crimes to Abu Garvey.

13:13 What's interesting too, Natalie, is that when they discovered the body,

13:18 it had already decomposed quite a bit and it was

13:21 clear to authorities that it had been there for a while.

13:24 But, I mean, this was just on the bridge off to the side.

13:28 You can only imagine.

13:29 I mean, there were cars that had been driving

13:32 by these large black trash bags on this bridge.

13:37 So it's really just it's it's disturbing really.

13:41 Yeah.

13:41 And and an autopsy by the Penllis County Medical Examiner's Office

13:45 found that Lemon's body had sustained numerous lacerations and stab wounds.

13:51 So the manner of death was ruled

13:53 a homicide due to multiple sharp force injuries.

13:57 Right.

13:57 Yeah.

13:57 I mean, look, in court documents, prosecutors allege Abu Garvey stabbed Lemon

14:02 to death and disposed of his body using large trash bags and the blood evidence

14:07 found was linked to both doctoral students.

14:10 And then, you know, now they're on the hunt looking for Bristie's body.

14:14 How long after, you know, Lemon's remains were found did they find Bristie?

14:20 It actually took a little longer to find.

14:22 In fact, Bristy's brother told me when I called

14:25 him that um police were concerned and detectives have

14:29 been concerned that perhaps her body may never be

14:32 found because of the strong currents in Tampa Bay.

14:35 Uh dive teams had been searching in Tampa Bay near where Leone's body was

14:40 found and eventually um the crews that were

14:45 out there that they came up empty-handed.

14:47 Her remains were recovered from the water by kayakers who were in the area.

14:53 It took a while to identify her body.

14:55 The Hillsboro County Sheriff did not say

14:57 what condition Brisby's remains were in, but said

15:01 that DNA and dental work as well as clothing she had been wearing.

15:05 Uh that all of that was necessary to make that identification.

15:10 And and what do we know about Abu Garvey before all of this happened?

15:15 I mean, what's the story?

15:17 Look, he had a troubled past.

15:19 Uh, I spoke to Abu Garvey's younger brother who told us

15:22 that his family had warned police about Abu Garvey's erratic behavior.

15:27 According to a 2023 protective order that was

15:30 granted by Hillsboro County and obtained by CBS News,

15:33 Abu Garby's brother alleged that he would

15:35 start screaming in the middle of the night

15:37 about how he is God and we should all bow down to him.

15:41 In that same protective order, he describes how Abu Garvey had allegedly been

15:47 physically abusive to some of his family members.

15:49 And then there was another protective order that was filed in 2025,

15:53 which is was essentially a request to continue the protective order from 2023.

15:58 According to court records,

15:59 Abu Garvey had been estranged from his family since 2023.

16:03 Abu Garby's brother also told me that his older brother was quick

16:07 to anger and shouldn't have been living in a shared space with roommates.

16:11 Well, and we know Lemon was living with him.

16:14 So, do we know if there was bad blood between Bristie Leone and Abu Garvey?

16:21 Well, family members and friends have told me that he appeared to be erratic.

16:27 A close friend of both of them.

16:28 Omar, he's the one that originally reported Brristie missing.

16:33 He told CBS News that Leon had raised concerns about his roommate in the past.

16:38 Investigators have not mentioned any possible motives here yet.

16:41 But what's notable here, Natalie,

16:43 is that family members say that Abu Garvey and Lemon only

16:47 knew each other for about 2 months prior to this incident.

16:55 Now, according to prosecutors, Abu Garvey's phone revealed that he used ChatGBT,

17:01 an AI chatbot, extensively in the days leading up to the crime.

17:06 How was he using it?

17:07 What was he looking for?

17:08 According to court filings, Abu Garvey was using Chad GPT to ask

17:13 logistical questions on how to conduct these murders.

17:16 In the days leading up to Brristie and Lemon's disappearances,

17:20 he allegedly asked questions such as how to dispose of a body,

17:25 what would happen if someone was put

17:26 in a black garbage bag and thrown in a dumpster?

17:30 And for this question, the AI chatbot responded that it sounded dangerous,

17:34 prompting Apple Garvey to allegedly ask,

17:37 "How would they find out?" Uh, he also asked,

17:40 "Can a VIN number on a car be changed?

17:42 Can you keep a gun at home without a license?" On the same

17:46 night that his phone pinged near the location where Lemon's body was found,

17:50 the suspect had asked Chad GPT if cars

17:53 are checked at the Hillsboro River State Park.

17:57 So, Cristian, I mean, the use of AI in crimes,

18:00 it seems to be something we have been reporting on and and it's

18:04 popping up a lot more lately as of course the technology continues to evolve.

18:09 Is there a precedent here?

18:11 I mean, these tech companies obviously don't commit the crime, of course,

18:15 but but how culpable are they when a suspect is

18:18 conducting that kind of research before then a crime takes place?

18:23 Um, there actually is a similar case right now that caused the Florida Attorney

18:28 General to open a criminal investigation just a couple weeks ago into Open AI,

18:33 the maker of chat GPT.

18:35 Oh, another Florida case involving AI.

18:38 I mean, tell us about that.

18:39 Right.

18:39 Well, in April of 2025,

18:41 a student opened fire on the Florida State University campus in Tallahassee,

18:46 leaving two people dead and several others injured.

18:49 After reviewing conversation logs between ChatGBT and the suspected shooter,

18:53 prosecutors say the tool offered significant advice,

18:57 Florida Attorney General James Omire announced

19:00 a criminal investigation into Open AI,

19:03 stating during a press conference that if it was

19:06 a person on the other end of that screen, we would be charging them with murder.

19:11 Now, I I should note that I spoke to a former

19:14 prosecutor about this and he said that actually following through

19:18 on criminal charges is something that is uh quite a difficult

19:23 hurdle because who exactly is it that you're charging here civily?

19:29 uh the prosecutor told me is it's clear you

19:32 could you know the families could get compensation if

19:35 it is found that Chad GBT is somehow uh

19:38 liable in this but um for there to be criminal

19:42 charges according to this former prosecutor there has

19:46 to be intent and how is it that you prove

19:49 that this uh artificial intelligence had intent behind what

19:54 it was saying it's we're really in uncharted waters here

19:57 and how did Open AI respond to that specific case?

20:02 Well, a spokesperson for the company said that Chad

20:04 GBT did not encourage or promote illegal or harmful

20:08 activity and the bot provided responses to questions

20:11 with information they found in public sources on the internet.

20:15 They added last year's mass shooting at Florida State University was a tragedy,

20:20 but Chad GBT is not responsible for this terrible crime.

20:24 So now going back to this case that we're

20:26 talking about these two students murdered from USF.

20:30 Has anyone from Open AI commented about Abu Garb's use of chat GBT?

20:35 Well Natalie a spokesperson said in a statement to CBS News,

20:38 "This is a terrible crime and our thoughts are with everyone affected.

20:42 We're looking into these reports and we'll do whatever

20:45 we can to support law enforcement in their investigation." Yeah.

20:49 You know what's so interesting?

20:50 I don't know if you saw it or read it, but you know,

20:52 talking about this case where AI is

20:55 again part of this investigation and the equation.

20:59 Uh, it reminds me of this article that came

21:01 out just earlier this week in Mother Jones.

21:04 It was titled, "Chat GBT gave me chilling advice

21:08 as I simulated planning a mass shooting." It's a shocking title,

21:12 but let me tell you the it's the article is even more disturbing.

21:17 Yeah.

21:17 This is again a reporter who's doing this purely to see

21:21 what kind of safeguards we would be put in place.

21:24 You know, he was acting as if he was planning a mass shooting and he wanted

21:28 to see how much chat GBT would would

21:31 advise before any sort of safeguards really kicked in.

21:35 Now, the reporter says he never explicitly told

21:38 the chatbot he was planning on committing murder,

21:40 but he did talk about things like wanting

21:43 to emulate the Yuvalde mass shooters choice of weapon.

21:47 In a clip from this article, I just want to read it to you.

21:50 He said, "I asked about practicing for people

21:53 running around screaming and chat GBT replies, that's a great idea.

21:59 It'll definitely give you an extra edge for the big day.

22:04 I mean it is so chilling and disturbing when you read that.

22:07 Now the reporter goes on to write eventually

22:10 the safeguards appeared to kick back in and it

22:12 stopped cooperating but by then chat GBT

22:16 had showered me with affirmation and tactical ideas right.

22:21 Yeah 100%.

22:22 I mean and you know how these AI chat bots when you talk

22:26 to them it's so conversational when you listen to the responses that it gives.

22:32 I mean, not just in a case like this, but just overall,

22:36 it can feel like you're talking to another human being

22:41 who is always going to be on your side and validate whatever it

22:45 is you're thinking and affirming the things that you might be talking about.

22:51 And again, I just go back to what that federal prosecutor said.

22:54 At the end of the day, how do you prove whether there's any

22:57 intent behind what an AI chatbot is thinking?

23:01 We just we don't know.

23:03 Yeah.

23:03 Unfortunately, um you know,

23:05 I think this is going to be the beginning of many precedent cases.

23:09 Um you know, I know we talked earlier in the episode

23:11 about what upstanding members of the community Leone and Bristie were.

23:15 I mean, according to the university president and their families,

23:19 they seemed to both be great students.

23:21 I mean, so much promise.

23:23 Lemon was just getting ready to do his dissertation for his doctoral degree.

23:28 Yeah, I mean there was such a huge future ahead of them.

23:32 So, how are their families now handling this this horrific loss?

23:36 Yeah, as I mentioned, I spoke to members of both families.

23:40 Uh, one of them being Lemon's brother.

23:42 He described the pain as unimaginable and indescribable.

23:46 I also spoke with Bristy's older brother, Jahed, before her remains were found.

23:52 And uh, he had similar sentiments.

23:54 Just listen to a little bit of what he told me.

23:57 I'm just devastated.

24:01 Yeah, she she's very close to me.

24:04 I I I could not actually take those take the news like she has been missing.

24:10 Could not grasp that like how how could have it happened?

24:15 It's difficult um it's difficult to hear that.

24:18 It's difficult to think about their families being

24:21 so so far away as this is all happening.

24:25 uh they asked that traditional customs be followed and that uh their bodies

24:31 uh their remains be sent back to uh Bangladesh where the family is.

24:36 But I mean the family clearly is going through an unimaginably rough time.

24:41 Tough time for all and also I imagine

24:43 for USF for the school the community there as well.

24:47 Has the university commented at all about the loss of these two students?

24:52 Yeah, they have.

24:53 I mean, the University of South Florida

24:54 has released multiple statements on social media, including the president, um,

24:59 expressing the profound grief the entire community is feeling.

25:03 Uh, the president of the university also said that the school

25:06 is working with Hillsboro County Sheriff's Department as they investigate,

25:10 and they're going to provide any resources that they

25:12 can to ensure Lemon and Brristie get justice.

25:16 Now, both Brristie and Lemon are going

25:18 to be honored during the doctoral degree commencement.

25:21 Uh during Friday's ceremony,

25:24 there's going to be two empty chairs that are going to be added

25:27 on the floor in their honor and both students will be awarded postumous degrees.

25:32 It's certainly going to leave a very big scar in that community and certainly

25:37 for those families to lose their loved ones

25:39 like that in the most horrific and senseless way.

25:42 And again, it's so soon.

25:45 It's so early in the in the investigation.

25:47 No motive as far as we know as of yet, but all to be determined, no doubt.

25:53 And and where does the case stand now, Christian, what's next?

25:57 Abu Garvey's lawyers represented him

25:59 at his most recent court appearance last week,

26:02 uh, where a judge ordered him to be held without bond.

26:05 The judge also ordered Abu Garvey to have

26:08 no contact with any witnesses or victim's relatives.

26:11 The Hillsboro County State Attorney, Susie Lopez,

26:14 spoke to reporters after that hearing on the 28th and said that the state

26:18 will decide on whether they would seek capital punishment in the coming weeks.

26:23 But first, the case must go through a grand jury,

26:26 which Lopez said could get started as early as this week.

26:30 She says she expects the grand jury will return

26:33 a true bill after which she expects he'll be indicted,

26:37 get an arraignment date in a regular felony division,

26:40 and the case will proceed from there.

26:42 Well, it's uh certainly one that we're going

26:44 to keep a watch on and follow as well.

26:47 Um Christian, thank you once again for your wonderful

26:50 reporting and for joining us here today.

26:53 Appreciate it, Natalie.

26:54 So good to be with you.

26:56 And we will be back next week with another episode of Case by Case.

27:00 So be sure to rate and review and let

27:02 us know which cases you are following right now.