Before Season 2Edit
Mike and Lou were best men at each other's weddings. However, Mike used to regularly beat his wife, Julie. Also, Mike had been arrested several times for soliciting prostitutes, being drunk, and disorderly behavior. Each time, the charges against Holden were dropped on technicalities because his friend Lou intervened. Eventually, Julie took their son and left Mike, seeking refuge on a shelter for women.
At some point, Mike started a relationship with a prostitute called Dorea Pinchuk. He would also pick other prostitute so one of them could babysit Mikey, while he had sex with the other. He picked a prostitute called Carla a few times, mostly on weekends. However, Mike was still desperate to find Julie and his son, so he asked his friend Lou for the address of the shelter.
After getting the address for the shelter where his wife was hiding, Mike sent Dorea there to make sure Julie was there. After Dorea checked it out, she warned Mike. That night, he went into the shelter and murdered all six women, including Julie. He then fled with Dorea and his son, Mikey.
Later, Connie Riesler was looking for Mike. When he approached her, she decided to go with him wanting to earn the $5,000 reward for his capture. Mike then took Connie and Dorea to an apartment at 1530 Los Prisa. He then asked Connie to babysit Mikey while he had sex with Dorea on the other room. After some time, he came out and went to the room where Connie was. When Mike saw her on the phone, he asked her who was she talking to, but she told him she was arranging her next appointment. Mike then asked her to join them since Mikey was asleep.
At this point, Mike heard the police sirens outside the apartment. When he noticed Detective Vic Mackey outside, he took Connie as a hostage. Vic tried to negotiate with him, but he turn violent. Vic then decided to drop his weapon and Mike let him inside the apartment. He also asked him to lower the blinds because he knew there would be snipers pointing at him. As Vic got in, he tried to calm Mike by telling him he understood what he was feeling since he missed his children as well. Mike apparently sympathized with him but, at one point, felt he was lowering his guard and became violent again. When Vic tried to calm him more, Mike threw Connie against the wall and shot her in the abdomen to prove he wasn't joking around. Vic became enraged and upset and, taking advantage of Mikey distracting his father, he pulled down the blinds, allowing a police sniper and Shane Vendrell to shoot Mike twice in the chest, killing him.