District police are searching for a suspect they believed sexually assaulted seven elderly women over the last eight months in the Petworth and Mount Pleasant areas of Washington.

Police say the same man apparently raped or sexually abused all of the women, who range in age from 75 to 86. The first incident occurred last October; the latest on July 21.

Many of the women have difficulty walking, and two use canes. All are widows. They live in two-story row houses in the mostly black, quiet, middle-class area between Rock Creek Park and the U.S. Soldiers Home.

"It's highly unusual to have so many elderly women raped in one area," said George Baker, a detective investigating the cases. "I've never seen a pattern like this before."

The women described the rapist as black, 5-foot-5, of medium weight. He is in his late teens or early 20s, has close cropped hair and brown eyes. He has worn blue cutoffs and a grey T-shirt, a blue jogging suit, white coveralls, and jeans and a blue jacket.

In all but one case, the man raped or assaulted the women in their homes. He usually enters the house throught an unlocked door early in the morning, grabs the woman, forces her into a bedroom, and begins beating her with his fists.

Then he removes his clothes and hers, and forces her to participate in sexual acts. If she screams or resists, he usually ties her hands with a bra or scarf, or stuffs her mouth with clothing.

Finally, he takes her money and jewelry and flees, police said.

One of the women had a heart attack minutes after the rapist left her house. She spent a month in the hospital and is home now. All the women suffered bruises on their heads, chests or arms.

Police say the rapist is becoming bolder. At first, he sneaked into homes through unlocked doors, on three occasions, minutes after the woman opened the door to let a pet out. But in april, he began ringing doorbells and forcing his way into homes after a woman answered the door.

On July 21, he became even more aggressive: he rang a doorbell at 4 a.m., said that he was a messenger, and asked the woman to open the door so he could give her a letter. When the woman refused, he broke the glass of a first-floor window, stepped inside and raped her.

"I told him I had an operation but he wasn't paying no attention," the 85-year-old woman said as she sat on her porch on Irving Street NW. Her right arm, from her wrist to her elbow, was swollen and blue.

"I was pushing him away from me and the strain did that," she said, pointing to her arm. "The doctors took X-rays and they said it will be okay. I hope they don't send me a big bill."

In April, the man stuffed one of his victims in a bedroom closet and pushed a file cabinet in front of the door. The woman managed to get out of the closet and call the police.

"I was so frightened," said the woman, who lives on 4th Street NW. "After he put me in the closet, I listened very carefully to hear if he was still in the house. I was panting for breath. I had no clothes on whatsoever. I was just happy to be alive."

Now, she worries that the rapist will visit her again. She has had a new lock installed on the screen door. She no longer leaves her basement door open. And she has had the trees in front of her home trimmed so that her neighbors will be able to see intruders more clearly.

Her neighbors, like the neighbors of other elderly women who were raped, have made it their business to question strangers who come to her door.

"A man came to fix our gas stove the other day and the little boy next door stopped him before he even knocked," said the woman's sister, who lives with her. "The gas man said, "Lady, you sure have some good neighbors. I almost had to give that boy my fingerprints.""

Another time, she said, she yelled at her cat to make it stop clawing the rug. "I was yelling. "Stop it! Stop it!" The next thing I knew, the woman next door was calling out, "Are you okay in there?" She heard me through that side window."

Police believe the same man raped or sexually assaulted the seven women because he said similar things to them and abused them in the same ways. They also believe he may be responsible for burglaries in the neighborhoods. CAPTION: Illustration, Police sketch of suspect