Dan Markel — Case Archive

Law enforcement · FBI

Oscar Jimenez Jr.

Retired FBI special agent who conducted the April 19, 2016 undercover street approach to Donna Adelson in Miami and testified about it in four Dan Markel murder trials.

Appeared Garcia–Magbanua Magbanua Retrial Charlie Adelson Donna Adelson

414 lines · 11 appearances · 7 mentions · 4 trials

About

Jimenez is the firsthand source for the moment investigators applied pressure directly to the Adelson family and placed a covert phone number in their hands. He authenticated recordings of the operation in each trial, while the admission and publication treatment of particular exhibits varied. His testimony and repeated cross-examinations provide a firsthand record of the street approach and the recurring challenges to its design and documentation.

Across Trials

His account stayed remarkably stable across the four trials while the questioning around it shifted with each defendant. In the Garcia and Magbanua 2019 trial he faced two separate defense cross-examinations, one probing the limits of his gang expertise and his ignorance of wiretap coverage, the other pressing him on the "Katie" and "Tuto" references and on a 2019 deposition in which he could not recall exactly how the note was written. By the Magbanua 2022 retrial the cross had narrowed to the missing flyer and the script-as-roadmap argument, with the operation's design rather than his credentials as the target. In the Charlie Adelson 2023 trial his testimony took on a new evidentiary edge: the defense used his confirmation that the covert line worked throughout to set it against wiretapped statements that the number was dead, and the follow-up calls became the focus rather than the street approach itself. In the Donna Adelson 2025 trial, with the person he approached on trial, the emphasis moved to how she responded — his disclosure that hers was one of only three answered calls on the covert line, and his concession that he had been instructed to be "very polite," went to how much weight her reaction could bear. Across the trials he consistently described himself as carrying out instructions rather than designing the operation, leaving questions about investigative choices to the case agent.

Trial Record (18)

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

Trial Summary

Testified on the sixth day of trial as the retired FBI undercover agent who carried out the April 19, 2016 "bump" of Donna Adelson in Miami Beach, authenticating the body-camera, surveillance, and telephone recordings of that operation. Both defense teams cross-examined on the encounter's design, the agent's limited knowledge of the wider investigation, and the missing flyer.

Testimony (3)

Oscar Jimenez Jr. - Direct

Oscar Jimenez Jr. - Cross

Oscar Jimenez Jr. - Cross

Mentioned (1)

Patrick Sanford - Cross

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

Trial Summary

Retired FBI special agent who testified on the fifth trial day about the April 2016 undercover "bump" of Donna Adelson in South Miami, authenticating the flyer he handed her and the body-camera and surveillance recordings of the encounter.

Testimony (3)

Oscar Jimenez Jr. - Direct

Oscar Jimenez Jr. - Cross

Oscar Jimenez Jr. - Redirect

Mentioned (2)

Opening Statement - Sarah Kathryn Dugan

Patrick Sanford - Direct (Part 3)

CA Charlie Adelson Oct 26, 2023 – Nov 6, 2023

Trial Summary

Testifying on the trial's fourth day, the retired FBI agent described the April 2016 undercover "bump" of Donna Adelson and authenticated the flyer, recordings, and call logs generated by that operation.

Testimony (2)

Oscar Jimenez Jr. - Direct

Oscar Jimenez Jr. - Cross

Mentioned (4)

Opening Statement - Sarah Kathryn Dugan

Christopher Corbitt - Redirect

Patrick Sanford - Direct (Recall, Continued)

Charlie Adelson - Direct (Part 5)

DA Donna Adelson Aug 22, 2025 – Sep 4, 2025

Trial Summary

Testified on trial day 4 as the FBI undercover agent who carried out the April 19, 2016 "bump" of Donna Adelson outside her South Miami area, authenticating the flyer, recordings, and undercover phone records generated by that operation.

Testimony (3)

Oscar Jimenez Jr. - Direct

Oscar Jimenez Jr. - Cross

Oscar Jimenez Jr. - Redirect