Frank Mathers was born in Liberty City in 1945. At an unknown point in time he moved to Vinewood, San Andreas, to become a novelist. He eventually became a TV producer, producing such hit shows as "Angel and the Knight", "My Drunk Uncles" and "Just the Five of Us". He also had an interest in undersea exploration. In 1989, he married an unnamed woman and they had five children, but in 2009 he walked out on his family following an affair with his assistant Abigail Winthrop. Mathers and Winthrop later married, remaining married until Mathers' death in 2013. Reportedly, Mathers had a reputation for a strong work ethic, "uncompromisingly low standards" of entertainment and a "refusal to consider anybody else's feelings".
Events of GTA V
An internet article from Public Liberty Online published after completing the mission Blitz Play reports that Mathers drowned in an accident while he was testing a new submarine in the ocean near Paleto Bay. It states that a malfunction in the system caused the submarine to break apart, distributing its pieces across the Pacific Ocean, though the article states that Mathers' body was never found.
After his death, his wife Abigail enlisted Michael's help to find the submarine pieces so that she can "sleep much easier". After doing so, Michael and Abigail find a piece with Frank's last dying message on it, which says "someone tampered with the airlocks", which is damning evidence that Frank's death is foul play. Abigail nervously takes the evidence with her and quickly leaves, implying that she sabotaged Frank's submarine to kill him and receive his life insurance. Michael has the option to kill her or let her go.