Brock Turner, a former Stanford University swimmer convicted of sexually assaulting an unconscious woman, was released from jail on Friday after serving half of his six-month sentence.
He was released on the account of his 'good behavour'.
Turner's early release has sparked a renewed debate on sexual assault on US campus colleges.
Turner was jailed three months ago for assaulting with intent to commit rape, penetration of an intoxicated person and penetration of an unconscious person.
He was 19 when he was caught on the top of an unconscious woman near a dumpster.
Dozens of demonstrators took to the streets to protest against Turner's short jail time. They called for the removal of Judge Aaron Persky, who had sentenced Turner in June.
"Why am I so passionate? I have a 16-year-old daughter," San Jose resident Bonnie Montgomery said at the protest. "She's going to college next year and I want her to be safe."
The case drew attention when the victim read a powerful letter in the court. She also detailed the assault outside a fraternity house in January 2015 in graphic terms.
The case prompted California lawmakers to pass a legislation to expand the definition of rape. A legislation to ban probation in similar assault cases was also passed by the lawmakers. It needs to be signed by the Democratic Governor.
Turner was charged with sexual assault as he digitally penetrated the woman. California law doesn't recognise digital penetration as rape.
Persky sentenced Turner to only six months in county jail and three years probation, following recommendations from a probation report that described the case as "less serious due to the defendant's level of intoxication."
(WION with inputs from Reuters)