TNT’s Murder in the First is adding to its ranks for Season 2, casting CSI: NY vet A.J. Buckley in a new series regular role.

According to our sister site Deadline, Buckley will play Marty “Junior” Mulligan, brother to Kathleen Robertson’s Detective Hildy Mulligan.

A fellow San Francisco PD police officer, Junior will have been promoted into Hildy’s homicide investigation unit when Season 2 opens this summer.

Buckley’s other TV credits include last spring’s Justified run (playing Danny Crowe), Supernatural and Longmire.