Balco founder Victor Conte was released from prison where he spent four months for doping offences.
Conte was sentenced in October to four months in prison and four months' home confinement for his role in giving athletes performance-enhancing drugs.
Baseball star Barry Bonds' trainer Greg Anderson has already served a three-month prison sentence for money laundering and steroid distribution.
Balco vice-president James Valente was put on probation for his involvement.
Valente pleaded guilty to reduced charges of steroid distribution.
Anderson and Conte were also fined $10,000 and banned from owning firearms.
Their sentencing follows a probe into the California laboratory launched in 2003, involving raids by the United States Anti-Doping Agency (USADA) and the San Mateo County narcotics task force.
USADA accused Balco, the Bay Area Laboratory Cooperative, of being the source of the previously undetectable designer steroid THG (tetrahydrogestrinone).
The Balco scandal has involved some of athletics' top names, with Dwain Chambers and former world double sprint champion Kelli White both receiving two-year bans.
Conte was released early on Thursday from Taft Correctional Institution, where he was picked up by his family.
MLB to investigate steroid abuse
But investigators at Major League Baseball may choose to interview Conte about steroid use in the game after launching their own probe into alleged drug use.