Roland Pryzbylewski

Prez is sent to Lieutenant Daniels' Barksdale detail because Deputy Commissioner Burrell allows the unit commanders to dump their most incompetent officers on Daniels. Upon arrival, he accidentally shoots a wall while showing off modifications to his gun. Though appalled, Daniels agrees to keep Prez if Cantrell will also give him Leander Sydnor, the best detective under Cantrell's command.

Later, Prez, Herc, and Carver drunkenly incite a near-riot at the Franklin Terrace Towers, and Prez pistol-whips a teenager with his service weapon, blinding him in one eye. Notably, even the brutality-prone duo of Herc and Carver think Prez's actions are unjustified. Daniels stands up for his detective and protects him from serious repercussions by providing Prez with a suitable story for Internal Investigations; Prez is ultimately suspended from street duty, but Valchek thanks Daniels for helping Prez.

Stuck in the office, a bored Prez begins playing with the Barksdale organization's pager codes, eventually breaking them and greatly contributing to the case. Mentored by Freamon, he discovers a gift for wiretap work and following the paper trail, eventually becoming valuable to the team.

Prez confesses to his father-in-law that his earlier problems had largely been due to dissatisfaction with his traffic police work. He tells him that detailed case work had become his passion and that he wants to continue to work major cases. When Valchek starts feuding with Frank Sobotka, he requests a detail similar to the previous Barksdale detail. As in the previous case, Burrell gives him a team largely consisting of incompetent "humps".

Prez is given minor authority within the detail, but Lieutenant Grayson will not follow his recommendations on how to proceed. Prez tells his father-in-law that the detail is making little progress, and Valchek, after witnessing the unit, demands that Daniels be brought in as the unit commander, threatening Burrell's bid to become police commissioner.

When the focus of the investigation shifts away from Sobotka, Valchek angrily confronts the detail, berating Prez specifically. Prez stands up for their work and punches Valchek. With Prez facing charges of insubordination and assaulting a commanding officer, Daniels stands up for him again, pointing out that if there is an official inquiry the FBI agents present during the incident would affirm that Prez hit Valchek only after the latter had shoved and insulted him. Valchek agrees that Prez can return to the detail following a written apology and two months of working the midnight shift as a narcotics detective in his district.[3]

Prez joins Daniels' newly formed Major Crimes Unit. Late one night, while responding with McNulty to a distress call, Prez fails to properly identify himself and fatally shoots a plainclothes officer in a case of mistaken identity. He is brought up on administrative charges and suspended because the officer was African American, and the shooting is seen as being potentially racially motivated.

This prompts a hearing from both the courts and the Vanguard (Baltimore's African American police officer union). Horrified by what he has done, Prez quits the force despite Daniels, Caroline Massey and Lester Freamon (all of whom are African-American) agreeing to testify that they believe Prez is not a racist.

Prez starts a new career as a math teacher at Edward Tilghman Middle School. As a teacher, he becomes attached to the students in his classroom, even going as far as to assist neglected student Duquan "Dukie" Weems with laundry and food that his family does not provide for him (they are known to sell his possessions for drug money). After Randy admits to knowing about Lex's murder, Prez passes the information on to Daniels.

He later finds out that Randy has been labelled a snitch after Herc mishandles an interview with Randy and is disappointed with his friends at the precinct. Later, Prez discovers that Dukie is no longer attending middle school and is working on the corner. Prez sees through the school system's flaws, but adapts well, and becomes a dedicated teacher who enjoys helping his students advance through class.

Prez is only seen once in Season 5, appearing in the series finale "–30–". He has grown a beard, and appears to have become a capable and well-respected teacher. When Duquan "Dukie" Weems visits him and asks for money: ostensibly to pay rent and to enroll in a GED program, but actually to buy heroin. Prez agrees, but warns Dukie that if he is lying their friendship is over. Prez drives off disappointed but unsurprised when he sees Dukie using the money to support his newly-developed drug addiction.