Story highlights The case drew national attention for the three-month sentence imposed on Turner

The assault occurred in January 2015 at Stanford University

(CNN) The former Stanford University swimmer who was convicted last year of sexually assaulting an unconscious woman -- and spent only three months in jail -- is appealing his convictions and requesting a new trial.

Lawyers for Brock Turner filed an appeal Friday with California's 6th District Court of Appeal, claiming their client was denied due process during his 2016 trial and calling it "fundamentally unfair."

Turner was charged after two Stanford graduate students witnessed the assault taking place in January 2015 while they were riding bicycles near Stanford. He was 19 at the time.

A jury in Santa Clara County found Turner guilty in March 2016 on three felony counts: assault with intent to commit rape of an intoxicated or unconscious person, penetration of an intoxicated person and penetration of an unconscious person.

Key to Turner's request for a new trial is a statement the prosecutor repeatedly made during trial, saying the assault occurred "behind the dumpster."

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