Former Stanford University student Brock Allen Turner, whose conviction of sexual assault of an unconscious woman in March prompted national outrage, has been released after serving three months of his six-month jail sentence in California.

Turner, a three-time All-American swimmer, walked out of the Santa Clara County jail shortly after 6 a.m. with his head down and without speaking to the media, according to the Associated Press. He received "hundreds of pieces of hate mail," James Jensen of the Santa Clara County Sheriff's Office told ABC News.

Turner, 21, reportedly plans to live with his parents in his hometown near Dayton, Ohio, where he will be required to register as a sex offender within five days, according to Greene County Sheriff Gene Fischer.

Like other sex offenders, Turner will be monitored by a probation officer for three years. He is also banned from parks, schools and other places where children can gather, and must refrain from using drugs and alcohol.

Turner's lenient sentence created a firestorm of criticism for Superior Court Judge Aaron Persky, who cited Turner's lack of a criminal history and young age.

"A prison sentence would have a severe impact on him," Persky said. "I think he will not be a danger to others."

Persky, who is a Stanford graduate, received a flood of backlash and later asked to be assigned to civil court, which was granted. His ruling came prior to the recent bill approved in California that requires an actual prison sentence rather than time in a county jail for anyone who is convicted of sexually assaulting an unconscious or intoxicated person.