|First appearance||"The Detail" (Season 1 episode 02)|
|Last appearance||"–30–" (Season 5 episode 10)|
|Cause/reason||End of series|
|Created by||David Simon|
|Portrayed by||Jim True-Frost|
|Aliases||Prez, (Mister) Prezbo|
|Occupation||Police officer, public school teacher|
Prez has a well-known history of incompetence in the department. The incident most often cited is that he once shot up his own squad car in a panic, then called in a false report. He has been bounced around various units, and is considered an inept detective. Because he married the daughter of career officer (and political force) Stanislaus Valchek, he is protected from being fired, despite their mutual dislike. Prez had most recently been working in the casualty division under Lieutenant Cantrell prior to the series.
Prez is portrayed as a mostly intelligent and good hearted man, but unsuited to the often brutal realities of Baltimore police work. Despite his winning the respect of his colleagues in the Barksdale / Sobotka details through his data interpreting and paper chasing skills, he is never truly comfortable as a police officer. By contrast, he later becomes a committed and dedicated teacher.
Prez is sent to Lieutenant Daniels' Barksdale detail because Deputy Commissioner Burrell tells the unit commanders to dump their most incompetent officers on Daniels. Upon arrival at the detail, he accidentally shoots a wall while showing off modifications to his gun. Daniels is appalled, but agrees to keep Prez if Cantrell will also give him Leandor Sydnor, a highly respected detective.
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 then-violent Herc and Carver think Prez's actions are uncalled for.) Daniels stands up for his detective and protects him from serious repercussions by making up a story for Prez to tell Internal Investigations; Prez is ultimately suspended from street duty, but Valchek is pleased with Daniels for helping Prez.
Stuck in the office, Prez grows bored and begins playing with the pager codes the Barksdale crew uses, eventually breaking them and making a major contribution to the case. Under Freamon's mentorship, he discovers a facility for wiretap work and for chasing the paper trail, eventually becoming a valuable member of 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 told him that detailed case work had become his passion and that he wanted to continue to work major cases. When Valchek starts feuding with Frank Sobotka, he requests a detail similar to the previous Barksdale detail. Instead, Burrell gives him 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 seeing the unit at work, demands that Daniels become the unit commander, threatening to derail Burrell's quest to be police commissioner.
When the focus of the investigation shifts away from Sobotka, Valchek angrily confronts the detail, and berating Prez specifically. Prez stands up for their work and punches Valchek. With Prez facing charges of assaulting a commanding officer and insubordination, Daniels stands up for him a second time, 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 cursed at him. Valchek agrees that Prez can return to the detail following a written letter of apology and two months of working the midnight shift as a narcotics detective in his district.
Prez joins Daniels' newly formed Major Crimes Unit. When responding to a distress call, Prez fatally shoots a plain clothes officer in a case of night-time mistaken identity. He is brought up on administrative charges and suspended because the officer was African American, and the shooting was potentially racially motivated. Prez vehemently denies being racist but due to the press and Baltimore's majority African American population, the story leaks out and prompts a hearing from both the courts and the vanguard (Baltimore's African American police officer union). Prez is shocked at the fact that he killed another officer and quits the force though Daniels, Caroline Massey and Lester Freamon (all African-American) agree to testify that he did not kill Waggoner out of racial prejudice.
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 a neglected student Duquan "Dukie" Weems with laundry and food that his family do not provide for him (and in fact steal for drug money). After Randy admits to knowing about Lex's murder, Prez lets Bunk know. He is also aware of Randy being labeled a snitch and is disappointed with his friends at the precinct. Later, Prez discovers that Dukie is no longer attending high 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 the students advance through class.
Prez is only seen once in season 5, appearing in the series finale "–30–". He seems to have become a capable teacher who has authority after properly punishing a student who ruined another student's lunch. When Duquan "Dukie" Weems visits him asking him for money, supposedly for Dukie to support himself, but in reality to feed his new drug addiction, Prez agrees to give him the money, but tells Dukie that if he is lying, that will likely end whatever relationship they had. Prez drives off disappointed when he realizes Dukie is not using the money to support himself, but is not surprised.
The character's code breaking faculty, and the pager code itself from season one, are based on the Melvin Williams case investigated by Harry Edgerton and Ed Burns. His experiences as a teacher are based on those of Ed Burns, who retired from the police to become a teacher in Baltimore.
It is implied that the character has an affinity for the music of Johnny Cash, playing "I Walk the Line" while examining the work of the detail in "Storm Warnings" and "Ring of Fire" while cleaning his classroom in "Soft Eyes". It is worth noting that the montage set to "I Walk the Line" is one of the few in the series, the show generally reserving the convention for closure at the end of its seasons.