<Li> Chandler Kinney as Riana Murtaugh, Det . Murtaugh's teenage daughter . The character is based on Rianne Murtaugh, played by Traci Wolfe in the film series . </Li> <Li> Dante Brown as Roger "RJ" Murtaugh Jr., Det . Murtaugh's teenage son . He graduated from high school at the end of season 1 and briefly attended college before dropping out during season 2 . The character is based on Nick Murtaugh, played by Damon Hines in the film series . </Li> <Ul> <Li> Thomas Lennon as Leo Getz, a comedic ambulance - chasing lawyer who once worked in the District Attorney's office before being fired . He befriends Murtaugh (and to a lesser extent, Riggs) after he witnesses a client's murder, and is put under their protection . His friendship with the duo is strengthened in the second - season episode "Let it Ride" where he works with them again and Murtaugh assures Leo that they don't have to be on a case to be friends . Getz is partially inspired by the character of the same name played by Joe Pesci in the film series . </Li> <Li> Hilarie Burton as Karen Palmer (seasons 1--2), a DEA agent who sometimes works with Riggs and Murtaugh on drug trafficking cases, and is also Riggs' love interest . The two break up early in season 2 . </Li> <Li> Floriana Lima as Miranda Riggs (née Delgado) (seasons 1--2), Det . Riggs' late wife, who is seen in flashbacks . Originally from the Los Angeles area, she moved to Texas when she married Riggs, and after her death, he moved to LA and joined the LAPD . The character is based on Victoria Riggs from the film series, although she was never seen as she had already died before the events of the first film . </Li> <Li> Richard Cabral as Detective Alejandro "Alex" Cruz (season 1), formerly an undercover officer with the LAPD's Gang Division who once worked at the Robbery - Homicide Division . </Li> <Li> Tony Plana as Ronnie Delgado (seasons 1--2), the Los Angeles City Attorney and Det . Riggs' father - in - law . He is stabbed in prison in the Season 2 episode "Diggin' Up Dirt", and dies in the hospital . </Li> <Li> Andrew Patrick Ralston as Jim McNeile, a dentist and neighbor of the Murtaughs . </Li> <Li> Michelle Hurd as Gina Santos (season 2), a police big shot who arrives to take control of the division as chief, superseding the authority of Captain Avery . She and Murtaugh had previously partnered as detectives on a stakeout . </Li> <Li> Andrew Creer as Detective Zach Bowman (season 2), a young detective who starts working at the precinct . He is soon partnered with Bailey . Leo Getz condescendingly calls them "The B - team", which the naïve Bowman thinks is because their last names both start with "B". </Li> <Li> Kristen Gutoskie as Molly Hendricks (season 2), Riggs' childhood friend and the ex-wife of his old best friend Jake, who has been in and out of prison . Riggs and Molly have a brief relationship that Riggs ends when he sees his work is putting Molly and her son in danger . They later are able to reconcile . </Li> <Li> Rex Linn as Nathan Riggs (season 2), Martin Riggs' abusive father . </Li> <Li> Chase Mangum as Young Martin Riggs (season 2) </Li> <Li> Sophia Woodward as Young Molly Hendricks (season 2) </Li> <Li> Duncan Joiner as Ben (season 2), Molly's son via her ex-husband Jake . </Li> <Li> Peter Coventry Smith as Garrett Riggs (season 2), Riggs' half - brother . </Li> </Ul> <Li> Thomas Lennon as Leo Getz, a comedic ambulance - chasing lawyer who once worked in the District Attorney's office before being fired . He befriends Murtaugh (and to a lesser extent, Riggs) after he witnesses a client's murder, and is put under their protection . His friendship with the duo is strengthened in the second - season episode "Let it Ride" where he works with them again and Murtaugh assures Leo that they don't have to be on a case to be friends . Getz is partially inspired by the character of the same name played by Joe Pesci in the film series . </Li>

Who plays riggs father on lethal weapon tv show