Baltimore police were investigating whether the reported rape of a woman Sunday morning in Reservoir Hill was related to other recent sexual assaults, department officials said.

The woman was sleeping in her first-floor apartment in the 2400 block of Callow Ave. when she awoke about 7 a.m. and saw a man standing above her, according to Agent Donny Moses, a police spokesman. The man apparently came in through an open window and made his way to her bedroom, Moses said.

The woman told police that the suspect covered her mouth and sexually assaulted her, then forced her to clean herself.

Police do not believe the man was armed, but Moses said the victim was unable to provide a detailed description of the suspect.

Sunday's incident appears similar to three burglary-rapes and one incidence of sodomy reported between May 2008 and November 2009, said the Police Department's chief spokesman, Anthony Guglielmi.

However, "we don't have conclusive forensic evidence yet," he said. As a result, "it's premature to say whether [the Callow Avenue incident] is related to earlier incidents."

Baltimore Police Commissioner Frederick H. Bealefeld III has authorized the crime lab to prioritize testing of samples from the Callow Avenue scene, but it will take 10 to 15 days to obtain results, Guglielmi said.

Police were able to develop sketches of two men suspected of other rapes last fall that took place outdoors near bus stops. A joint task force of homicide detectives and sex offense investigators has been working to solve the crimes, Guglielmi said, and the department created a 24-hour tip line, 888-223-0033, which is still operating.

"We've received a lot of public support and community intelligence," Guglielmi said. No tips have led to an arrest, but "we're going to follow up on every lead we get."

About 120 rapes were reported last year in the city through mid-December, the most recent data available.