A 20-year-old St. Paul man has pleaded guilty for his role in the armed robbery of two University of Minnesota students earlier this year, the Hennepin County attorney's office said Monday.

Javonta Williams is expected to be sentenced to 36 months in prison after being convicted of aggravated robbery, according to prosecutors' spokesman Chuck Laszewski. Williams accepted a plea deal on Dec. 15, the day his trial was scheduled to begin.

Prosecutors said his accomplice, Lavelle Grayson, 23, of Minneapolis, was sentenced earlier this month to 48 months of prison time after pleading guilty to the same charge.

The robbery occurred on the morning of July 30, as two students, a man and a woman, were walking back to their dorm rooms from the Seven Corners area. As they approached the West Bank end of the Washington Avenue Bridge, they were confronted by Williams and Grayson, one of whom was armed with a handgun, and instructed to "put your face in the grass and give us everything you've got," according to court documents.

Williams and Grayson took the victims' cellphones, cash, IDs, and credit and debit cards before fleeing, prosecutors said. The thieves tried using one of the cards at three Minneapolis light-rail stations.

Someone later turned in the gun that police believe was used in the robbery, which had been stuffed into a backpack and left near an SUV parked in a downtown Minneapolis parking lot. The victims' IDs were found in the backpack, authorities said.

Following a string of similar crimes on campus earlier this year, the university spent about $3.1 million to hire additional police officers and to install new and brighter lighting and security cameras.

Libor Jany • 612-673-4064 Twitter:@StribJany