Officials with the department said police had received a tip earlier this month that women were engaging in prostitution at various locations in town through advertisements that were placed on Backpage.com, a classified advertising website that has reportedly been used in the past as a messaging board for prostitution. Police said undercover officers responded to an ad posted on Backpage for sexual services at the Howard Johnson motel on Stony Hill Road on July 7 when Lilian Dossantos, 34, of Danbury was arrested after offering to perform sexual acts in exchange for money.