In the first incident, the attacker tried to sexually assault a teenage girl as she slept in her bedroom in Temple Hills on July 18. Police said the girl kicked her attacker until he gave up and ran from the house.

Two weeks later, police said, a 32-year-old woman was awakened by an unknown man, who raped her in her bed and then fled her Temple Hills home on foot.

Last week in the 2400 block of Colebrooke Drive in Temple Hills, it happened again.

Police said a 10-year-old girl was awakened by an armed man; he held a knife to her and tried to sexually assault her. A relative, who had returned to the home about 5:45 a.m., startled the attacker, causing him to flee.

The three cases occurred only a short distance apart, leading investigators to think they might be related, said Cpl. Debbie Carlson, a Prince George's County police spokeswoman.

But more than a week after the most recent attack, few tips have been phoned in to the department, she said.

"We need the community's help to solve these crimes," Carlson said.

Investigators said the manner in which the attacks occurred indicates that the same person might be responsible. In the first case, police said the suspect entered a house in the 2800 block of Iverson Street about 2:40 a.m.

On July 31, someone entered a house in the 3800 block of 28th Avenue about 6:30 a.m. Police said both victims gave very similar descriptions of the suspects.

Although it is a vague sketch, police described the suspect as black, about 20 years old, between 5-foot-3-inches and 5-foot-7-inches, and about 140 pounds. They said he wears his hair in two Afro puffs, one on each side of his head, and that he wore a dark-colored hooded sweatshirt in the most recent attack.

Anyone with information should call the department's Crime Solvers unit at 301-735-1111. A reward of up to $1,000 is being offered for the tip that leads to the arrest and indictment of a suspect.