Name: Brock Dietz — Direct/Cross - Day 1 - Magbanua Retrial
Uploaded: 2022-05-18
Description: Brock Dietz, a forensic video analyst with 28 years in law enforcement, testifies on direct examination to authenticate surveillance footage compilations from Premier Gym cameras, ATM still images, and Star Metro bus cameras. Six exhibits — raw source files and highlight clips — are admitted without objection. Defense waives cross-examination.

Brock Dietz, a forensic video analyst with 28 years in law enforcement, testifies on direct examination to authenticate surveillance footage compilations from Premier Gym cameras, ATM still images, and Star Metro bus cameras. Six exhibits — raw source files and highlight clips — are admitted without objection. Defense waives cross-examination.

Day 2 →

Proceedings

Direct Brock Dietz - Direct Line 1

Cross Brock Dietz - Cross (Waived) Line 84

Direct Brock Dietz Georgia Cappleman

1 5:16:24

JUDGE WHEELER: Thank you for everybody's promptness, and we're ready to continue with the testimony. And Ms. Cappleman, the state may call its next witness.

2 5:16:32

MS. CAPPLEMAN: The state calls Brock Dietz.

3 5:16:34

JUDGE WHEELER: Brock Dietz, please.

4 5:17:09

JUDGE WHEELER: Good afternoon.

5 5:17:12

JUDGE WHEELER: Before you have a seat, we're going to swear you in. If you could please raise your right hand and respond to the clerk.

6 5:17:17

COURT CLERK: Please solemnly swear or affirm that the testimony you shall give shall be the truth, the whole truth, and nothing but the truth.

7 5:17:22

BROCK DIETZ: I do.

8 5:17:23

JUDGE WHEELER: Thank you. Please have a seat.

9 5:17:29

MS. CAPPLEMAN: Sir, please introduce yourself and spell your name.

10 5:17:32

BROCK DIETZ: Good afternoon. My name is Brock Dietz, first name B-R-O-C-K, last name Dietz, D-I-E-T-Z.

11 5:17:42

MS. CAPPLEMAN: How are you employed, sir?

12 5:17:43

BROCK DIETZ: I'm currently a law enforcement detective with the State of Florida's Bureau of Fire, Arson, and Investigations.

13 5:17:49

MS. CAPPLEMAN: How long have you been doing that?

14 5:17:51

BROCK DIETZ: 28 years.

15 5:17:52

MS. CAPPLEMAN: All right. What about in 2014? What were your duties there?

16 5:17:55

BROCK DIETZ: I was still in arson investigations, but I also have other duties which include forensic video analysis.

17 5:18:04

MS. CAPPLEMAN: What training and education do you have in the area of forensic video analysis?

18 5:18:08

BROCK DIETZ: I've been performing forensic video analysis since 2002.

19 5:18:12

BROCK DIETZ: For the past 20 years, I've analyzed over 830 different video and audio submissions. The training that I've had has occurred from not only public agencies such as the FBI and Virginia State Police, but it also comes from private institutions and also forensic organizations.

20 5:18:32

BROCK DIETZ: I've been to 15 different classes as either a student or a lecturer involved in video analysis, and again, I've done over 830 different submissions.

21 5:18:42

MS. CAPPLEMAN: All right. And were you asked to analyze or clarify some videos in reference to the State of Florida versus Katherine Magbanua?

22 5:18:49

BROCK DIETZ: Yes, I was.

23 5:18:49

MS. CAPPLEMAN: All right. And does that include bus video?

24 5:18:52

BROCK DIETZ: Excuse me?

25 5:18:53

MS. CAPPLEMAN: Bus video.

26 5:18:53

BROCK DIETZ: Correct.

27 5:18:54

MS. CAPPLEMAN: ATM video or ATM stills?

28 5:18:58

BROCK DIETZ: Correct, the stills. Still images.

29 5:19:00

MS. CAPPLEMAN: And Premier Gym surveillance video.

30 5:19:03

BROCK DIETZ: That is correct.

31 5:19:03

MS. CAPPLEMAN: All right. I want to start with Premier Gym.

32 5:19:07

MS. CAPPLEMAN: Judge, at this time, I would ask to introduce into evidence State's 117, that is the raw data from Premier Gym pursuant to stipulation.

33 5:19:19

JUDGE WHEELER: All right. For the record, any objections?

34 5:19:22

MR. DECOSTE: No, Your Honor, no objections.

35 5:19:23

JUDGE WHEELER: All right, so 117, the Premier raw data, will be admitted as State's 117.

36 5:19:30

MS. CAPPLEMAN: Thank you, Judge. So you were provided with all the images from the Premier Gym around the time in question, right?

37 5:19:38

BROCK DIETZ: That is correct.

38 5:19:39

MS. CAPPLEMAN: And they had a bunch of different cameras mounted at that facility, correct?

39 5:19:44

BROCK DIETZ: Exterior cameras and interior cameras.

40 5:19:46

MS. CAPPLEMAN: And did you create — we'll just tell the jury what you created out of the raw data that you were provided in State's 117.

41 5:19:46

BROCK DIETZ: Okay. When I was presented the evidence with the video, I was asked by the State, and at that time they had identified the victim's vehicle, the victim himself, and the suspect's vehicle, and I was asked by the State to highlight those images — when those vehicles and the victim and the suspect's vehicle came in the frame of view — to highlight them so that it would be easier for the judge and jury to be able to take a look at it.

42 5:20:24

MS. CAPPLEMAN: All right. And Judge, at this time, I would ask to introduce the clips provided by the witness as State's Exhibit 89.

43 5:20:32

JUDGE WHEELER: Any objection from the defense?

44 5:20:35

MR. DECOSTE: No, Your Honor.

45 5:20:36

JUDGE WHEELER: Be admitted as State's Exhibit 89.

46 5:20:41

MS. CAPPLEMAN: Permission to publish that exhibit?

47 5:20:43

JUDGE WHEELER: Yes.

48 5:20:52

MS. CAPPLEMAN: Actually strike that. We're gonna publish it just not right — let's move on. All right, I want to talk about the ATM video. What did you do in reference to the raw data that was provided to you in reference to the ATM images in this case?

49 5:21:10

BROCK DIETZ: Simply made still images from them.

50 5:21:12

MS. CAPPLEMAN: I'm gonna approach and show you State's 37 through 43.

51 5:21:52

MS. CAPPLEMAN: And accurate images of what you retrieved off the ATM raw data?

52 5:21:58

BROCK DIETZ: Yes, ma'am.

53 5:21:59

MS. CAPPLEMAN: And where was the ATM data?

54 5:22:04

BROCK DIETZ: I'm not familiar with it, but it was just provided by law enforcement.

55 5:22:08

BROCK DIETZ: Yes, ma'am.

56 5:22:08

MS. CAPPLEMAN: So at this time, I'd ask to move into evidence 37 through 43.

57 5:22:14

JUDGE WHEELER: Any objection?

58 5:22:16

MR. DECOSTE: No, Your Honor.

59 5:22:17

JUDGE WHEELER: Be admitted as State's Exhibits 37 through 43.

60 5:22:21

MS. CAPPLEMAN: All right. And then I also wanted to show you state's 4.

61 5:22:55

MS. CAPPLEMAN: Let me ask you first, before I show you State's 4 — were you provided with some raw data from the Star Metro bus company here in Tallahassee?

62 5:23:04

BROCK DIETZ: Yes, I was.

63 5:23:04

MS. CAPPLEMAN: And did you analyze that data looking to isolate some images in particular?

64 5:23:04

BROCK DIETZ: Correct. I was able to isolate the victim's vehicle as well as the suspect's vehicle.

65 5:23:17

MS. CAPPLEMAN: And that was from cameras mounted on the outside of city buses?

66 5:23:22

BROCK DIETZ: Yes, that's correct.

67 5:23:22

MS. CAPPLEMAN: Judge, at this time I would ask to introduce, pursuant to stipulation, State's 118, which is a thumb drive containing the raw bus surveillance data.

68 5:23:38

JUDGE WHEELER: All right. Any objection?

69 5:23:41

MR. DECOSTE: No objection.

70 5:23:42

JUDGE WHEELER: Be admitted pursuant to stipulation as State's Exhibit 118.

71 5:23:47

MS. CAPPLEMAN: All right, and then at this time, Judge, I'd also like to introduce State's 90, which is the exhibit prepared by this witness containing the clips of the bus data.

72 5:23:57

JUDGE WHEELER: Any objection?

73 5:24:00

JUDGE WHEELER: Be admitted as State's Exhibit 90.

74 5:24:04

MS. CAPPLEMAN: Now I'm going to show you State's 4.

75 5:24:06

MS. CAPPLEMAN: I'm just asking if you recognize that as one of the images that came off of the raw bus data that you were talking about.

76 5:24:18

BROCK DIETZ: I'm just —

77 5:24:19

MS. CAPPLEMAN: Is that accurate?

78 5:24:20

BROCK DIETZ: It is.

79 5:24:24

MS. CAPPLEMAN: I'd ask at this time to introduce State's Exhibit 4 into evidence.

80 5:24:28

JUDGE WHEELER: Any objection?

81 5:24:30

MR. DECOSTE: No objection.

82 5:24:31

JUDGE WHEELER: State's Exhibit 4 is admitted into evidence.

83 5:24:34

MS. CAPPLEMAN: And no further questions at this time.

Cross Brock Dietz Christopher DeCoste

84 5:24:39

JUDGE WHEELER: Cross-examination?

85 5:24:41

MR. DECOSTE: No cross, Your Honor.

86 5:24:43

JUDGE WHEELER: All right. Can we excuse the witness?

87 5:24:46

MS. CAPPLEMAN: He may be excused, Judge.

88 5:24:47

JUDGE WHEELER: All right. Thank you, sir. You are excused. Have a good day.

Insights

Direct Brock Dietz

State forensic video analyst Brock Dietz is qualified and testifies about processing Premier Gym, ATM, and Star Metro bus surveillance footage — authenticating compiled clips and still images that isolate the victim's and suspect's vehicles across three independent camera sources.

Case Significance

Dietz's testimony clears the evidentiary path for the State's primary surveillance record linking the suspect vehicle to locations relevant to the investigation. The admitted exhibits will be published to the jury in subsequent proceedings.

Suspect vehicle isolated across three independent camera sources — gym, ATM, and city bus
All six exhibits admitted without defense challenge, securing the foundation for jury-facing publication

Highlights

Procedural

Dietz is qualified as a forensic video expert: 28 years in law enforcement, 20 years of forensic video analysis, more than 830 submissions, and training from the FBI, Virginia State Police, private institutions, and forensic organizations.

Evidence

Premier Gym raw surveillance data (State's 117) and Dietz's compiled highlight clips (State's 89) are admitted without objection. Dietz explains he was asked to highlight the victim's vehicle, the victim, and the suspect's vehicle as they appeared in frame.

“I was asked by the State, and at that time they had identified the victim's vehicle, the victim himself, and the suspect's vehicle, and I was asked by the State to highlight those images — when those vehicles and the victim and the suspect's vehicle came in the frame of view — to highlight them so that it would be easier for the judge and jury to be able to take a look at it.”

— Brock DietzDietz explains the scope and deliberate curation of his enhancement work — the compiled clips are purpose-built to focus the jury's attention on the victim's and suspect's vehicles, framing the surveillance evidence as identification evidence rather than raw footage.Evidence

ATM still images (State's 37–43), Star Metro bus raw surveillance data (State's 118), compiled bus clips (State's 90), and a specific bus camera still (State's 4) are all admitted without objection — completing the evidentiary foundation for the State's surveillance video case.

People Mentioned

Dan Markel

Evidence Mentioned

State's 117 State's 118State's 37–43State's 4 State's 89 State's 90

Deep Analysis

Attorney Strategy

Clean foundation pass, publication deferred

Cappleman moves briskly through all six exhibits using stipulations and waived objections to admit the surveillance evidence without showing it to the jury — preserving the visual impact of the compiled clips for a dedicated publication session.

Case Theory Connections

Vehicle tracking evidence

The admitted exhibits form the State's primary surveillance record linking the suspect vehicle to locations relevant to the investigation. Dietz's work isolating vehicles across three independent camera systems strengthens the evidentiary chain supporting the State's theory of pre-crime surveillance and flight.

Evidentiary Or Procedural Notes

All exhibits admitted without objection

State's 117, 89, 37–43, 118, 90, and 4 are admitted either pursuant to stipulation or with express defense waiver. No evidentiary challenge is raised at this stage.

Publication of State's 89 deferred mid-examination

Cappleman withdraws a publication request for the compiled Premier Gym clips (State's 89) mid-sentence, indicating those clips will be shown to the jury in a later proceeding rather than during this foundational examination.

Followup Questions Or Open Threads

Compiled clips not yet published

State's 89 (Premier Gym clips) and State's 90 (bus clips) were admitted but not published to the jury during this examination. The evidentiary core of Dietz's work — the curated vehicle-tracking footage — remains to be shown in a subsequent proceeding.

Testimony Themes

Surveillance foundation

Dietz authenticates raw footage from Premier Gym, ATM, and Star Metro buses and explains how he isolated and highlighted the victim's and suspect's vehicles across all three sources to aid jury review.

Witness Role And Importance

Witness Role And Importance

Brock Dietz is the State's forensic video analyst, called to authenticate and explain surveillance footage from three independent sources. His role is foundational: his testimony clears the evidentiary path for compiled clips and still images that will be shown to the jury to track the suspect vehicle in the days surrounding the murder.

Cross Brock Dietz

Defense waives cross-examination of forensic video analyst Brock Dietz; witness excused.

Case Significance

Procedural close of a foundational witness's testimony; the defense did not challenge the admitted video evidence or Dietz's methodology.

Defense waiver of cross-examination
No rulings, objections, or contested exchanges

Deep Analysis

Witness Role And Importance

Witness Role And Importance

Brock Dietz was the State's forensic video analyst who authenticated surveillance compilations isolating the victim's and suspect's vehicles. The defense chose not to challenge his testimony or methodology.

Summary

Brock Dietz takes the stand as the prosecution's first afternoon witness. Dietz has 28 years of law enforcement experience, 20 of them in forensic video analysis, with more than 830 submissions. He describes being tasked with isolating the victim's vehicle, the suspect's vehicle, and Dan Markel himself across footage from Premier Gym security cameras, ATM still images, and Star Metro city bus exterior cameras. On direct by Georgia Cappleman, six exhibits are admitted — both the raw source recordings and Dietz's compiled highlight clips — pursuant to stipulation or defense waiver, without objection. Cappleman defers publication of the Premier Gym clips to a later session. Defense counsel DeCoste waives cross-examination, and Judge Wheeler excuses the witness.

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