The Georgia Bureau of Investigation charged Michael Robert Williams with felony theft by taking and violating his oath of office.
Athens-Clarke police Chief Jack Lumpkin fired the probationary officer just prior to his arrest. He was on the police force for just six months.
"Any time a law enforcement official betrays the public trust, it's a sad day," Lumpkin said Tuesday. "Certainly, we are disheartened that this recruit would conduct himself in such a manner."
Williams, 45, allegedly stole an Apple iPhone when he and another officer went to the student's apartment early the morning of July 19, police said.
The woman noticed the phone was missing a few days later and reported it stolen, though she didn't name the officer as a suspect, said Jim Fullington, special agent in charge of the GBI's Athens office.
"She just said they responded to her residence, and later she realized her phone was missing," Fullington said.
Fullington and Lumpkin would not disclose how Williams became a suspect, and the GBI agent said it's against policy to say if Williams made any statements about the allegations.
"We do not discuss admissions or confessions," he said. "The investigation substantiated the charges."
Lumpkin fired Williams on Tuesday afternoon, and soon afterward a Clarke County Superior Court judge signed arrest warrants. Williams still was in uniform when the GBI agent arrested him.
Williams joined the Athens-Clarke Police Department in February. He previously spent a number of years as an officer in the state of Washington, Lumpkin said.
He completed his Georgia police academy training but was under the supervision of a field training officer when he allegedly stole the iPhone.
Williams was released from the Clarke County Jail on Tuesday after he posted a $10,000 bond.