BUFFALO, Feb. 18 — When Albert and Mary Capozzi speak of their older son, Anthony, they recall a gentle boy who would take his mother into another room to tell her his secrets. They describe an athletic teenager who spent so much time playing basketball that he referred to a local recreation center as House 2.

Such memories have sustained the Capozzis for three decades, as Anthony first withdrew into a world devastated by schizophrenia, and then was arrested in connection with a string of rapes in the early 1980s that terrorized the neighborhoods around Delaware Park, the city’s largest.

Convicted of rape in 1987, Anthony Capozzi has spent the 20 years since then in state prison psychiatric wards.

All the while he, his parents, his three sisters and his brother have maintained his innocence.

“It has been hell,” Albert Capozzi, 81, a retired millwright, said while sitting at the dining room table in the home on Buffalo’s west side where he and his wife, Mary, 75, raised their family. “My wife and I, we don’t go to bed at night without thinking of Anthony. I can’t even concentrate on things I like to do. All my thoughts are with him.”

Last month, the arrest of another man in a different series of long-unsolved attacks provided the Capozzi family with new hope for Anthony’s release and exoneration.

On Jan. 15, the police arrested a factory worker, Altemio Sanchez, after reviving an investigation of a series of rapes and killings dating to 1986. A grand jury indicted Mr. Sanchez in two of the killings, those of a college student, Linda Yalem, on a bike path in 1990 and of another young woman, Majane Mazur, two years later. The police said they believed Mr. Sanchez had also committed at least eight other rapes and one other homicide.

Because of the five-year statute of limitations on rape cases, Mr. Sanchez cannot be charged with any of the rapes in which he is suspected.

His lawyer, Andrew C. LoTempio, has said Mr. Sanchez maintains his innocence.

Detectives involved in the Sanchez case have speculated that Mr. Sanchez may also have committed the two rapes in 1984 of which Mr. Capozzi was convicted.

“These cases are so similar — it just couldn’t be two different people,” said Detective Dennis Delano, who investigated Mr. Sanchez. “I can’t eliminate Sanchez as a suspect in those two earlier rapes.”

At least two of the rapes of which Mr. Sanchez is suspected took place in Delaware Park, as did two of the three for which Mr. Capozzi was tried.

The chronology of the rapes that the police claim Mr. Sanchez committed overlaps with that of the attacks for which Mr. Capozzi stood trial. One that the police now attribute to Mr. Sanchez was in 1981, before the Delaware Park rapes; another occurred in 1986, while Mr. Capozzi was in jail awaiting trial.

The victims of those two rapes, and of some others, provided a description of their attacker — short and stocky, with dark hair and a mustache — that fits both Mr. Capozzi and Mr. Sanchez.

But they estimated the rapist’s weight at 150 pounds, a figure Mr. Capozzi had long since exceeded as a result of medication he took for schizophrenia. His lawyer, Thomas D’Agostino, citing medical records, said Mr. Capozzi weighed at least 205 pounds at the time.

“He had no exercise — zero,” said Pamela Guenther, the youngest of Mr. Capozzi’s sisters. “He was lethargic and medicated and eating constantly. He was fat.”

Mr. Capozzi’s illness, which prevented him from holding a job, also rendered him incapable of carrying out the attacks, Mrs. Guenther said.

“He couldn’t get anything together, including the clothes he was going to wear that day,” she said. “To plan it, to get away with it, to get out of the scene and know he had to hide the stuff, absolutely not.”

In addition, Mr. Capozzi has a three-inch scar above his left eye, a detail that Mr. D’Agostino said was never mentioned by the witnesses at his trial. In a police report, one victim described her assailant’s face as scarred by acne; Mr. Capozzi’s skin is smooth.

And victims of three rapes that Mr. Capozzi had been suspected of, but did not stand trial for, did not pick him out of a lineup. Mr. Capozzi was acquitted of one rape but, despite a lack of physical evidence, he was convicted of two rapes and sentenced to a term of 11 2/3 to 35 years.

Although Mr. Capozzi, now 50, has already served almost twice the minimum sentence he received, the state’s Board of Parole has declined to release him, citing his refusal to admit responsibility for the assaults. Since his appeals ran out in the late 1980s, he has been in several prison psychiatric wards.

Mr. Capozzi is scheduled to appear before the Parole Board on March 13. But Mrs. Guenther says her brother’s legal team will seek a postponement of at least a month to look for additional evidence.

In the arrest of Mr. Sanchez, genetic testing played a crucial role. The police say his DNA — which undercover officers obtained at a restaurant where he and his wife had gone for dinner — matches evidence found at the scene of at least eight crimes, including the killings of Ms. Yalem, Ms. Mazur and Joan Diver, a mother of four whose body was found along a trail outside Buffalo.

Such testing was not admissible at the time of Mr. Capozzi’s trial, and evidence that now might be definitive in establishing his guilt or innocence, like semen that investigators found after one rape, was destroyed after his appeals and the statute of limitations ran out.

“If that exists, that would be the key to the door,” said Mr. D’Agostino, the lawyer. “But I’m told that it doesn’t exist.”

The Erie County district attorney, Frank Clark, acknowledged the lack of physical evidence supporting Mr. Capozzi’s conviction, but said: “The presumption of innocence has been removed — he’s now presumed to be guilty. I recognize that questions have been raised, but the coincidence that exists right now does not create a doubt in my mind. I need facts to create a doubt.”

Albert Capozzi said parole for his son would not be enough.

“That’s not clearing his name — that’s what we want,” Mr. Capozzi said. “Our name is involved. We’ve carried the stigma of this on our family for 22 years.”