[2] A regular through the entire run of the series from 1993 to 1999, Munch is a cynical detective in the Baltimore Police Department's Homicide unit, and a firm believer in conspiracy theories.

Munch is based on Jay Landsman, a central figure in David Simon's 1991 true crime book Homicide: A Year on the Killing Streets.

[3] Upon the cancellation of Homicide in 1999, Belzer was offered a regular role as Munch on the Law & Order spin-off titled Special Victims Unit.

On SVU, Munch becomes a senior detective in the New York Police Department's Special Victims Unit, and is first partnered with Brian Cassidy (Dean Winters), followed by Monique Jeffries (Michelle Hurd), and Fin Tutuola (Ice-T).

In the following episode, "Wonderland Story", Cragen and the squad throw Munch a retirement party, where past and present colleagues and family members celebrate his career.

Munch's return to help his friends in the SVU seventeenth-season episode "Fashionable Crimes" marks the 23rd season that the character has appeared on television in any capacity.

Barry Levinson, co-creator and executive producer of Homicide, said Belzer was a "lousy actor" during his audition when he first read lines from the script for "Gone for Goode", the first episode in the series.

It is explained that Munch had retired from the Baltimore Police Department, taken his pension as a Maryland state employee, and moved to New York to join a sex crimes investigation unit, where he was eventually given a promotion to sergeant.

[7] During the fourth-season premiere of Homicide: Life on the Street, he signs up to take a promotion exam in hopes of becoming a sergeant, but a "comedy of errors" prevents him from showing up for it.

In the first episode of the ninth season of Law & Order: Special Victims Unit, it is revealed that he passed the NYPD sergeant's exam, having taken it on a bar bet, and earned his promotion.

Andrew, however, reacts badly to his antidepressant medication, which triggers a manic episode that results in his taking a personal vendetta against a suspected rapist/murderer SVU is investigating, eventually killing the man by pushing him in front of a subway train.

[19] In a deleted scene from the third season of Homicide, Munch mentions to both Meldrick Lewis (Clark Johnson) and Tim Bayliss (Kyle Secor) that he had an uncle who lived up north but was unsure of what became of him – this is presumably Andrew.

Although he considered himself to be a "dangerous radical" due to his left-wing views, conspiracy theories and involvement with anti-Vietnam War protests, the FBI believed that he was a dilettante and posed no threat.

[21] Munch's partner at the start of Homicide is Stanley Bolander (Ned Beatty), an experienced police detective with more than 20 years under his belt.

In SVU, Munch is first partnered with Brian Cassidy (Dean Winters), whom he treats as a surrogate younger brother, alternately poking fun at him and imparting questionable advice on life and women.

When Fin gets frustrated over a potential witness being unable to testify due to relapsing on heroin, Munch mentions a former partner – likely Tim Bayliss (Kyle Secor) – who took cases like that personally and eventually committed suicide as a result.

[26] In Homicide, along with Tim Bayliss and Meldrick Lewis (Clark Johnson), Munch is co-owner of "The Waterfront", a bar located across the street from their Baltimore police station.

Following the events of the season 15 episode "Internal Affairs", Cragen informs Benson that Munch has submitted his retirement papers.

[31] In a later episode, Fin relates that Munch has married for a fifth time, his new wife being a rabbi, and that he has moved back to Baltimore and resumed ownership of the Waterfront.

[33] Homicide: Life on the Street: Law & Order: SVU: The following are the medals and service awards worn by NYPD Detective Munch, as seen in "Alternate".

Munch interacts with an Orthodox Jewish witness, using one Yiddish word, farshteyn ("understand"), and referring to the twelve Israelite tribes from the Bible.

Munch has been described as a stubborn man who distrusts all women, all forms of government and authority, and "can smell a conspiracy at a five-year-old's lemonade stand".

[37] Before leaving Baltimore, Munch had divorced Billie Lou after discovering she had been having an affair with a member of his own precinct after less than one day of marriage.

[34] In the season 1 finale of SVU, a police psychiatrist notes that despite his cynicism regarding relationships, Munch still believes in true love and is devastated by the fact he has not yet found it.

As the two catch up, he agrees to arrange for the funeral of Gwen's mother despite the fact his ex-mother-in-law loathed him and did everything in her power to disrupt her daughter's marriage to him.

While Munch could never be accused of being sentimental, his cynical façade has occasionally slipped, revealing a deep compassion for children born from his unhappy childhood.

When Munch emerges unscathed from an ambush shooting during a third-season episode of Homicide that leaves three of his colleagues hospitalized, he tries to laugh it off but breaks down in tears.

A 2007 news item noted the character of Munch "has slowly disappeared from [SVU's] plotlines", and quotes Belzer as saying "[i]t's mystifying to me", admitting his feelings to be "slightly hurt".

[44] Following season nine, in which Munch appeared in just over half of the episodes, Belzer reiterated his mystification at the development but also seemed to want to tone it down: "It's like yanking the tonsils out of the gift horse if I complain too much.

Along with his main cast roles on Homicide and SVU, Munch, or Belzer portraying a parody of the role, has also appeared as a character in other TV series, movies, talk shows, albums and comic books: Munch has become the only fictional character, played by a single actor, to physically appear on 10 different television series.