Brock Turner was convicted in March of three felony sex abuse charges for assaulting an unconscious woman on Stanford University's campus, and last week was sentenced to six months of jail time and three years probation, although he could have received a decade in state prison.

More than 100,000 people have signed a petition demanding the judge in the case, Aaron Persky, be removed from the bench over the sentence. The case's prosecutors have said the "punishment does not fit the crime ." Turner's father, meanwhile, has argued that the ex-Stanford swimmer's life has been ruined over "20 minutes of action."

But if it weren't for two strangers riding bikes on campus that night, Turner might not be spending a single day in jail.

"I can't understate how important those two heroes were in this case," Santa Clara County Deputy District Attorney Alaleh Kianerci told The Huffington Post on Monday.

Few reports of sexual assault ever lead to prosecution , let alone prison time. Between 8 and 37 percent of rapes result in prosecution, according to one study funded by the Department of Justice . National estimates suggest that for every 100 rapes, only five rapists will go to prison.

Many campus rape cases aren't prosecuted because there aren't witnesses and because victims can have imperfect memory of what happened, particularly when alcohol is involved. For example, Turner's victim was unconscious when police found her, and she had no recollection of the assault. Her blood alcohol level was three times the legal limit for driving.

And so it's possible there never would have been any charges pressed against Turner if it weren't for Stanford graduate students Peter Jonsson and Carl Fredrik Arndt.

Without their intervention, "we wouldn't know who the perpetrator was," Kianerci said. "Those two heroes made this case a prosecutable one."

Just before 1 a.m. on Jan. 18, 2015, Jonsson and Arndt were riding their bikes along a path near the Kappa Alpha fraternity. Jonsson told the cops that movement by a dumpster caught his eye, and he saw a guy on top of a female who was lying on her back, according to a police report.

At first, Jonsson and Arndt assumed the interaction was consensual. But Jonsson said he noticed that the female wasn't moving as he peddled by. "Something seemed weird," he told police, because the woman appeared to be unconscious.

Jonsson and Arndt approached the dumpster and yelled "Hey" to the guy who was later revealed to be Turner. He took off running, according to the police report. Jonsson realized the woman was passed out and chased after Turner, eventually catching and tripping him, the police report said.

Officers responded to a call about an unconscious female near the Kappa Alpha fraternity about 10 minutes later, according to the report, and found Jonsson and Arndt holding Turner on the ground. Witnesses told police that Turner had possibly sexually assaulted the woman who was lying next to the dumpster. Her dress was pulled up and her underwear was missing.

The cops arrested Turner at the scene for attempted rape, and he acknowledged in an interview that he had penetrated the woman's vagina with his fingers, according to the report. The woman did not regain consciousness until 4:15 a.m., and had no memory of the assault.