Riverdale Road is a heavily traveled roadway lined with small shopping centers, numerous apartment complexes and clusters of private homes in Prince George's County that has recently become the focus of a police investigation following a string of 26 sexual assaults.

County police officer Carol Landrum said yesterday that police believe the assaults, including four rapes, were committed by the same man. Most of them have occurred on the stretch of road connecting Riverdale and New Carrollton, between 64th and 79th avenues. The Baltimore-Washington Parkway cuts across Riverdale Road near 64th Avenue and several attacks have occurred in the woods along that roadway, according to Landrum.

The assaults began in August 1983 and the last attack, a rape, was reported on Sept. 10, she said.

When police began to suspect that the assaults were related, they stepped up their surveillance of the area, said Capt. David Mitchell of the Hyattsville police station. However, when leads in the case did not materialize, Landrum, who runs the county's Crime Solvers program, aired a report about the cases on television several weeks ago. So far, Landrum said, she has not received any useful calls about the case.

Despite the number of incidents in the area, many residents along Riverdale Road said they had not been aware of the attacks.

One of the victims, who was grabbed by a man outside her apartment building, said she has not changed her routine, but now carries a can of oven cleaner in her purse, which she plans to spray on any future attacker.

"I'm not a person who frightens easily, but now I'm a hell of a lot more aware when I go out," she said.

The woman, 47, who asked not to be identified, was told by police that her assailant, who ran away when she struggled and yelled, fit the description of the man involved in other attacks. He wore a dark blue sweatshirt and jogging pants, she said.

It was about 6 a.m. when the man grabbed her from behind as she was wiping off her car windows, preparing to go to work, she said. She could not give a clear description of his face because his sweatshirt hood was pulled down over much of his face, she said.

Anthony Salvemini, president of the Frenchman's Creek Condominium board of directors, said, "A lot of single women are afraid of leaving the safety of the building to go into the parking lot." The 608-unit complex borders Riverdale Road.

Salvemini said his condominium complex had doubled its security force on certain nights and increased the visibility of the security officers, who are off-duty county police.

"It's almost like nobody can go out anymore," said Ronnie O'Branovich, 35, a coordinator of a mental health "hotline" based in the area. "My staff is here until midnight by themselves . . . . What is Riverdale doing to make sure people who have to stay out at night are safe?" she asked.

According to police, most of the attacks have involved women between the ages of 18 and 24 who were walking, jogging or standing alone at bus stops in the morning. All of the attacks have occurred between 3 a.m. and 9:30 a.m., Landrum added. "He usually grabs them from behind," said Landrum and then he drags them out of view, sometimes into stairwells or laundry rooms.

The victims have described their assailant as a man between the ages of 18 and 22, with sandy brown hair. He is about 5 feet 9 inches tall and often wears a light blue or gray, hooded sweatsuit.