For 44 years Wilma Hennessey of Alexandria believed he was her son. Now she isn't sure.

"I just want to know if I brought the right baby home from the hospital," Mrs. Hennessey said. "If it were you, wouldn't you want to know?"

The white-haired woman discovered four years ago that the footprints of her only son, Barry W. Hennessey, now 48 and a Northern Virginia real estate broker, do not match the footprints on her son's 1936 birth certificate.

"It was the beginning of four years of hell," he says.

Mrs. Hennessey made the discovery while she was considering "making an ashtray for Barry using his footprint as the design." Then she ran across his May 15, 1936, birth certificate from Mercy Hospital in Denver. "Anyone could tell that those prints were completely different from the ones I had of Barry," she says.

And as the FBI and other experts will state, footprints, like fingerprints, can be used for positive identification and do not alter substantively with age.

Wilma Hennessey knows this. That's why she says she has spent four years crisscrossing the country trying to find the son she gave birth to at 11:52 a.m. May 15, 1936.

Barry Hennessey, a softspoken man, said he remembers another date vividly. It was Oct. 19, 1980, the day his mother showed him a report from a fingerprint analyst who had compared his adult footprint and his baby print and said they did not come from the same person.

"I looked at the report and wanted to jump out the window," he said. "I felt like I wasn't a human being. All of a sudden I had no idea who I was."

Tracking down the owner of the Mercy Hospital footprint hasn't been easy. Mrs. Hennessey first pleaded with the Colorado hospital to open their records of babies born about the time as her son so she could compare footprints. The hospital declined, saying confidentiality laws forbid it. The hospital has said it can't resolve the question of whether Mrs. Hennessey was given the wrong baby.

"Practically speaking, it would be impossible to do anything about this," said Michael T. McConnell, a Denver attorney representing Mercy Hospital. No one who worked with newborn infants at the hospital is still employed there, he said. "To bring in a fingerprint examiner to look at the records of babies born around that time May 15, 1936 would breach the confidentiality laws."

Even if the hospital could track down males born then and ask their permission to have a third party view their birth records, McConnell says they might say, "No."

"If she raised him as her son, he is her son," argues Eugene W. Whitwam of Washington, the retired FBI agent and fingerprint consultant who compared Barry Henessey's footprints. "This is just going to cause a lot of hard feelings."

"I haven't been able to sleep, I want to know what happened," says Mrs. Hennessey, the widow of a career federal government employe. "Either someone at the hospital put the wrong footprint on my son's certificate . . . or . . . , ' " she says, her voice trailing off.

"I don't know who or where my son is. Is it so wrong to want to know that? I'm not going to be around much longer?" Determined to resolve the question, Mrs. Hennessey flew out to Denver in 1980, found a cubbyhole in the city library and pulled the microfilmed 1936 copies of The Rocky Mountain News. After copying all male May birth announcements, she dusted off old telephone directories and called dozens of people with surnames listed in birth announcements.

When she talked to one man who said his son was born on May 16, 1936, she said her heart started skipping. Mrs. Hennessey got the man's address and flew to meet him.

The man, the Rev. Ralph C. Hodges, pastor of Western Hills Baptist Church in Wichita Falls, Texas, says he'll never forget the day Mrs. Hennessey introduced herself after a Sunday worship service. "She said to me: 'This may come as a surprise to you, but you may be my son.'

"I could see she was very distraught," Hodges said, so when she asked him, the pastor said he took off his shoes and socks, let her roll ink on his foot, and stepped on a piece of white bond paper.

When she looked at the print, Hodges said, "I could sense her emptiness. It wasn't what she was looking for."

Wilma Hennessey says she didn't want to tell Barry, but, because Mercy Hospital wouldn't release any of her medical records without his consent, she said she had no choice.

Colorado hospital and legal authorites familiar with Hennessey's predicament say they sympathize with her feelings, but see only more headaches and distraught people if she continues her search.

Dr. Thomas M. Vernon, the executive director of the Colorado Health Department says his powers of overseeing the state's hospitals do not include forcing a hospital to open medical or birth records. "The only mechanism to do that is the courts," he said.

A judge could order the hospital to look at the records, said Dr. Richard B. Lehmann, the director of the Colorado Bureau of Investigation's forensic lab. "This whole thing is bizarre," Vernon said, but it "comes down to balancing privacy rights against public rights."

Is Hennessey's right to know who her son is, strong enough to justify potentially disrupting many others' lives? "I don't know," Vernon says.

"It's sad what happened," said Denver attorney Jon T. Lozow,, one of the dozen attorneys Wilma Hennessey unsuccessfully approached to take on her case. "I told her when she walked in off the street four years ago that the hospital was going to stonewall her all the way on this," Lozow said.

"I explained that this kind of case didn't have much precedent and would take a lot of time and money to get it through the courts," the lawyer said.

Barry Hennessey says he doesn't have the energy or funds to legally battle the hospital. "I don't even care how the mistake happened," Barry Hennessey said. "I just want to know who I am."