Montgomery County Police have arrested a 21-year-old Gaithersburg man they say sexually assaulted a woman in Gaithersburg in December.

Christopher Johnson, of the 9300 block of Willow Creek Drive, in the Verandahs neighborhood of Gaithersburg, was arrested Feb. 7 and charged with first-degree assault, first-degree sex offense, and robbery, police said.

He was being held without bond, pending a bond review scheduled for today at 1pm in Rockville.

According to police, at around 9:40 a.m. on Dec. 7, the 28-year-old female victim walked into a laundry room in an apartment complex in the 700 block of Quince Orchard Boulevard. The suspect followed her in, police said.

The suspect pulled out a knife and sexually assaulted the victim. He then took some of the victim's personal property and fled on foot, police said.

DNA evidence collected from the scene was run through the Maryland Combined DNA Index System, and Johnson's profile was a match, according to police.

Correction: Montgomery County Police originally identified Willow Creek Drive as being in Montgomery Village. It is part of Gaithersburg.