Expert witness · Florida Department of Law Enforcement

Brock Dietz

Forensic video analyst who testified for the State in the 2019 Garcia–Magbanua trial and the 2022 Magbanua retrial about Premier Gym and city-bus footage, with the 2022 record additionally covering ATM still images.

Appeared Garcia–Magbanua Magbanua Retrial

97 lines · 5 appearances · 2 trials

About

Dietz is the person who connects the raw July 18, 2014 surveillance recordings to the processed video exhibits jurors were shown, so his examinations document the provenance and handling of a significant share of the case's video evidence. His testimony traces the Premier Gym and city-bus footage in both trials and, in the 2022 Magbanua retrial, the additional ATM still images, including what was and was not changed along the way.

Across Trials

Dietz occupied the same seat in both trials — the State's forensic video witness — but the treatment of his work differed sharply. In the 2019 Garcia–Magbanua trial his testimony was contested at length: defense cross-examination did not dispute his technical method but drew out that the State Attorney's Office identified the vehicle and person of interest before his work began, that he edited the footage five separate times at the prosecution's direction over five years, that an interval showing the victim in his car was removed from the processed Premier Gym exhibit at the State's request, that he prepared no side-by-side comparison of original and processed video, and that he returned the original media after copying it. The State used redirect to recast the disputed "alterations" as circles drawn around items of interest on copies. By the 2022 Magbanua retrial, overlapping footage passed with far less friction: six exhibits were admitted without objection by stipulation or waiver, the defense declined to cross-examine at all, and Judge Wheeler excused him with no credibility challenge on the record. The retrial presentation expanded to six exhibits and also included ATM still images.

Trial Record (5)

GM Garcia–Magbanua Sep 26, 2019 – Oct 11, 2019

Trial Summary

Testified on trial day 1 as the State's forensic video witness, explaining how he "clarified" the Premier Gym and city bus surveillance footage admitted as State's Exhibits 124 and 125, and acknowledging on cross that the State Attorney's Office identified the vehicle and person of interest and directed five rounds of edits.

Testimony (3)

Brock Dietz - Redirect

Day 1

KM Magbanua Retrial May 18, 2022 – May 27, 2022

Trial Summary

Called as the State's forensic video analyst, Dietz authenticated surveillance source footage and highlight compilations from Premier Gym, ATM, and Star Metro camera systems; the defense waived cross-examination.

Testimony (2)

Direct

Brock Dietz - Direct

Day 1 Cross

Brock Dietz - Cross (Waived)

Day 1