Williamson was acting strange Monday morning, the roommate said.
"We wake up to Eric running around the house with nothing but a work hardhat on, butt naked," the roommate said.
"I was upstairs, downstairs without clothes on for several hours," Williamson told NBC4 Wednesday. "And then I ended up putting pants on when I guess that act got old I ended up putting some pants on."
On Wednesday, investigators told FOX 5 they have reason to believe there may have been another incident in which someone saw Williamson naked in front of his window. They're asking anyone who may have seen Williamson in the nude through his windows to come forward, even if it was at a different time.
Police are especially concerned because the house is located across the street from a bus stop for school children.
Police wouldn't release the incident report or the name of the mother who filed the complaint. FOX 5 has learned she is a respected member of the community, and just happens to be the wife of a Fairfax County Police officer.
FOX 5 also spoke with some of Williamson's roommates, and they said they believed Eric was drunk on Monday morning when they were all leaving for work around 5 a.m. The alleged exposure happened around 8:30 a.m. Williamson, however, says he was drinking on Sunday night, but was not drunk on Monday morning.