Early Life
Tommy Vercetti was born in 1951, in Liberty City. The exact date, and the name of his mother and father are not known. His father owned a printing shop, and Tom would've liked to follow in his footsteps, yet led a different life. Some dialogue indicates that Tommy may have had a bad relationship with his mother.
Early 1970's
Prior to 1971, Tom joined the Forelli family, and became a made man. As his power increased, this intimidated Sonny Forelli, and set up a surprise ambush on him. With no choice but to kill the 11 man that ambushed him, he was convicted of murder, and sent to prison.
1986
15 years later, Tom was released from prison, after Sonny Forelli 'pulled some strings' with his connections. Sonny decides that he is too well-known in Liberty City, and sends him to Vice City for safety.
After flying to Vice City, he immediately drives to the docks for a drug deal. When the deal goes bad, and is ambushed, one of the drug dealers is killed. When Sonny is informed of this ambush, he indicates that he would like both his money and drugs back.
Tom initially worked for Ken, and also started working for a variety of other people. As his power grows, he purchases a number of businesses around the city, to expand his turf, persay.
Sonny, growing more impatient by the day, sends men to Tom to get his money and his drugs. A gunfight ensues, and both Sonny and Lance are killed. Ken and Tom take over, making them the most powerful criminals in Vice City.
After 1986
Tom continued to run the underworld with Ken, though their friendship became strained as Ken delved deeper into his addiction of cocaine. Tom forced Ken to go to rehab, and he became clean, yet Tom refuses to speak to him, and cut off all ties.