Armed with a gun and adhesive tape, police said Arthur Henderson broke into apartments in Ross Township twice in two days this month, robbing the women inside and then raping them, once forcing a woman into her baby's room and assaulting her on the floor.

Mr. Henderson, 38, was arrested at about 3 a.m. today after police surrounded an apartment building on Wylie Avenue in the Hill District, though his address is listed at the Cascades Apartments, where one of the rapes occurred.

He was tracked down in a joint effort by Ross and Pittsburgh police, the county sheriff's department and the FBI. Federal agents were involved because of a warrant for Mr. Henderson, but the FBI wouldn't comment on its involvement or the $5,000 reward it had offered for information leading to his arrest.

Mr. Henderson is charged locally with counts of rape, aggravated indecent assault, involuntary deviate sexual intercourse, burglary, robbery, theft, illegally possessing a firearm, intimidation of victims, recklessly endangering another person, false imprisonment, indecent assault, making terroristic threats, unlawful restraint and possession of instruments of crime.

Mike Manko, a spokesman for the Allegheny County district attorney's office, said authorities were investigating whether Mr. Henderson was involved in a crime in South Carolina in which a victim helped police generate a composite sketch that resembled him. Mr. Manko said Mr. Henderson has family in South Carolina.

Blaine Jones, who is representing Mr. Henderson, called him a "loving family man" and said his family proclaimed his innocence. He said that he plans to have an independent lab examine DNA results that linked Mr. Henderson to the crimes.

In a criminal complaint, police detailed the assaults in which they say he targeted two women who had been out walking their dogs.

In the first incident, which occurred on the morning of Jan. 7 at the Woodhawk Club apartment complex, a woman told police from a hospital room at UPMC Passavant that she was out walking her dog when she spotted a man outside she did not recognize. The complaint identified her attacker as Mr. Henderson.

When she returned to her apartment and attempted to close the door, the man forced his way in and brandished a handgun, then locked the door and secured the security bar.

"He told the victim to do what he said and she would not get hurt," police wrote in the complaint. "He said he just needed money."

The woman gave him $60 to $80 in cash along with three bank cards, writing down her PIN for him.

He told her he needed to take her clothes off so she could not run away, according to the complaint, then raped her twice.

Later, he asked her for an identification card and warned her he knew who she was and that he would come back if she reported the assault to police.

He retrieved a roll of duct tape from a box he had carried into the apartment and bound her hands behind her back, taped her ankles together and put tape over her mouth.

Less than two days later, early Jan. 9, police said Mr. Henderson struck again, attacking a woman at the Cascades Apartments.

That woman told police she took her dog out for a walk early in the morning, going out as her fiance slept. When she returned, the alarm clock was ringing.

She told police she found it odd, because her fiance never let their alarm continue to sound because he did not want to wake their four-month-old child.

When she returned to the master bedroom, she found her fiance lying face down on the floor with his hands tied behind his back. She turned and saw a man the complaint indentified as Mr. Henderson standing in the bedroom with a gun.

The man forced her to lie on her stomach and then handed her a roll of clear box tape. He asked her to unravel it for him so he could tie up her fiance.

She was unable to, and offered to get duct tape from downstairs.

Mr. Henderson followed her downstairs, according to the complaint, warning her fiance to not do anything stupid because "I have your girl."

The two returned to the master bedroom, where Mr. Henderson duct-taped her fiance's feet and hands, according to the complaint. The two gave Mr. Henderson the key to a safe and he took $400 from it, according to the complaint.

Mr. Henderson asked the woman what was in the other room. She told him it was her baby's room. He forced her into the room, where he told her to take off her clothes and bound her hands, feet and mouth with tape and raped her, according to the complaint.

It was no clear from the complaint where the baby was at the time.

Then he forced the woman back to the master bedroom to get her engagement ring, she told police. the complaint says he took the ring and an additional $100. He then warned the couple that he would "definitely" come back and kill them if they called police, according to the complaint.

Mr. Henderson was pulled over as he left the Cascades Apartments that morning because he was driving a blue Ford SUV that had been seen leaving the Woodhawk Club complex after the first assault. His girlfriend, who lived at the complex, was riding in the passenger seat.

He was later taken in for questioning and submitted a DNA sample but was released because police said they did not have evidence to charge him.

The DNA sample was later matched to material taken from the women who reported the rapes, prompting police to obtain a warrant for his arrest.

Mr. Henderson was in the Allegheny County Jail this morning awaiting arraignment on the charges.