Thomas Maier was the grieving father of Molly Maier and the husband of Teri Maier. His daughter was the San Joaquin Killer's, first victim.
Blinking Red Light[]
In Blinking Red Light, he was constantly in contact with James Panzer getting details and updates about James' research on the killer. He and Teri talked to Patrick about their daughter, and he showed Patrick to Molly's room.
Patrick found a DVD of Molly practicing her dance to "What A Wonderful World" by Louis Armstrong. They watched it and Patrick left him to continue watching it.
Always Bet On Red[]
Towards the beginning of the episode, it is revealed that Tom killed himself.
After it was revealed that the man he trusted to find his daughter's killer was revealed to be his daughter's killer, he became increasingly depressed. He eventually committed suicide by hanging himself, without even leaving a suicide note.
During the episode FBI agent Susan Darcy, was investigating the murder of James Panzer by Red John. Even though Red John was thought to have been killed by Patrick Jane, the murder of Panzer looked like a Red John hit. Susan started running with the angle that Panzer was killed by a Red John copy cat because Patrick Jane insisted to her that he killed Red John.
As Red John hates copy cats, he started stalking Susan. As Susan wasn't going to let it go, Patrick used Tom as a means to set him up as the murderer of James Panzer. He manufactured evidence by using Tom's hand to create hand prints on a knife and used James Panzer's blood on some close to create blood spatter. Patrick also created a suicide note written with Tom's forged hand claiming responsibility for the murder of Panzer.
Reading the fake suicide note gave Teri some closure as she thought he was weak for killing himself.