Turner was found guilty in March of three felony charges: assault with intent to commit rape of an intoxicated/unconscious person, penetration of an intoxicated person and penetration of an unconscious person.
The January 2015 assault -- digital penetration -- was stopped by two men on bicycles who noticed that the victim wasn't moving, authorities said. Turner fled, but the witnesses tackled him and held him until police arrived, according to the Santa Clara District Attorney's Office.
Turner was facing up to 14 years in prison. Prosecutors asked for six years, but Judge Aaron Persky sentenced Turner on June 2 to six months in jail and three years' probation, as recommended by the probation department.
Why 3 Months in Jail?
Turner's scheduled release date is Friday, Sept. 2, three months after his sentencing. But the shortened time served isn't uncommon. Many inmates in California only serve half of their sentences.
ABC News' chief legal analyst Dan Abrams said that "for many crimes, including this one, you get 50 percent of the time off for good behavior." While California and other states do this, it varies based on the crime and the state, he said.
What Was Turner's Life Like Behind Bars?
Turner -- who was a Stanford freshman during the January 2015 assault -- turned 21 during his three months in jail in Santa Clara County.
James Jensen of the Santa Clara County Sheriff's Office told ABC News that Turner received hundreds of letters of hate mail.
Jensen said Turner "got several hate mail early in his sentence, and he told us he didn't want to receive any more mail. So we kept his mail."
The mail will be given to Turner when he leaves, Jensen said.
During his time in jail, Turner has been in protective custody, which means he lives with other protective custody inmates. While they are separated from general population inmates, protective custody inmates are not in individual cells or solitary confinement, Jensen said.
And during his sentence, Turner has lived "just like any other inmate in protective custody." The inmates have recreational time outside of their cells during which they can make calls, shower and attend classes. Jensen said he doesn't know if Turner attended any classes.
Turner will be released like any other felon, but there will be extra security, Jensen said, noting there have been threats against him, but no specific threats.
The sheriff will be at Turner's release to make sure "everything runs smoothly," Jensen said, and to "make sure there is no special treatment."
What's Next for Turner?
When, as expected, Turner leaves jail Friday, he'll still have restrictions. First, Turner has three years of probation.
"He has to stay out of trouble," Abrams said. "He has to not get convicted of another crime. He has to abide by all the requirements from the probation department, and if he doesn't, he could end up back behind bars."
The judge also mandated that Turner register as a sex offender.
"It means wherever he goes in the country, wherever he lives, the local authorities will be informing residents that a sex offender is in their neighborhood," Abrams said.
"It will impact his ability to live a normal life in a lot of ways," Abrams said. "And that'll be something that will stay with him for the rest of his life."
After Turner's release, he's expected to return to his hometown in Greene County, Ohio.
Greene County Sheriff Gene Fischer told ABC News on Wednesday that he's waiting for paperwork from California. Fischer said within five days of Turner's return to Ohio, the former Stanford student must go to the Greene County Sheriff's Department to be photographed and registered as a sex offender.
Postcards will be mailed to alert nearby homeowners that a sex offender lives in the area, Fischer said.
Once Turner is photographed and registered, he is free to go, Fischer said. No ankle bracelet is given and monitoring will be done by sheriff’s deputies. Turner can expect a visit from deputies soon after leaving the sheriff's department, Fischer said.
"Brock Turner is very lucky that he's a free man," Abrams said. "But as a registered sex offender, and being Brock Turner, I've got to imagine that life will not be that easy."
What's in store for Turner's life post-jail may be unique because of all the attention surrounding his case. Turner's victim read an emotional letter in court during sentencing that went viral. Judge Persky was criticized for what many critics said was a sentence that was too lenient, and he is now moving off criminal cases, returning to the civil division.
California lawmakers, who called Turner's sentence "shockingly lenient," were inspired to introduce a bill based on Turner's case that is now heading to California Gov. Jerry Brown. The bill, AB 2888, aims to ensure that anyone in California convicted of sex assault can't be sentenced to probation.
Sex assault victims advocate Michele Dauber, who knows Turner's victim and is also a law professor at Stanford, told ABC News, "any notoriety that he has ... is unfortunate, but it's his fault."
"All of this is a result of a choice that Mr. Turner made," Dauber said. "He chose not to plead guilty for that crime ... and instead go to trial. ... All the way until the end, did not accept responsibility, did not express remorse."
However, in Turner’s statement to Judge Persky, obtained by ABC News in June, Turner states, in part: "There isn’t a second that has gone by where I haven’t regretted the course of events I took on January 17th/18th."
"I made a mistake, I drank too much, and my decisions hurt someone. But I never ever meant to intentionally hurt [redacted]," Turner goes on to say in his statement.
Dauber said she hopes that when Turner is released from jail, that he "finds a way to have a productive and appropriate life in society and doesn’t re-offend," she said. "My concern about him is that he was sent absolutely the wrong message by the judge," by being sentenced to six months.
Dauber said the sentencing sent a dangerous message to Turner and other potential perpetrators on college campuses.
Turner "got the message that he’s special, the rules don’t apply to him," she said. "He’s going to get a special deal that wouldn’t be available to regular people, because he’s an elite athlete, because he’s at Stanford. That’s such a dangerous message to have sent to an offender."
Dauber said Turner's quick release from jail also has a negative impact on the victim.
"Now that he is released, she's always going to feel some anxiety and fear. Every time she sees ... an individual who resembles him,” she said. That’s a "natural part" of being a crime victim, she said, but added, Turner's release "shouldn’t have happened this quickly."
Gary Goodman of the Santa Clara County Public Defender's Office -- who was not an attorney for Turner -- noted that Turner will be watched, will be on probation and will be registered as a sex offender.
"It was a bad mistake on that night," Goodman told ABC News. "Nothing indicates it's anything more or less than that. And he will suffer the consequences for the rest of his life."
Turner's family and attorneys declined to comment to ABC News.
ABC News' Jenna Harrison, Matt Gutman and Harry Traynor contributed to this report.