Feb. 20, 2006 — -- Susan Power had spent half a year trying to find her brother after he vanished with little trace on his way to work.
But last week, Raymond Power Jr., a suburban New York lawyer, turned up in a Chicago homeless shelter. He had amnesia and didn't know who he was.
Susan Power flew to Chicago to bring her brother back home.
"It was just unbelievable, just seeing him," Power said. "It was my brother and he looked at me and had no idea who I was. But I said, 'I'm sorry this stranger is hugging you, but I've been waiting seven months to do this.' "
Power is now back in a New York suburb and trying to get back to the life he says he lost for six months because of amnesia.
The husband, father and successful lawyer was last seen heading to work on Aug. 1. He said goodbye to his wife and children before leaving his Westchester County home, north of New York City, and heading to his law office in nearby White Plains.
His family says cameras captured him pulling into his normal parking spot at work. Seconds later, the car pulled out again.
He would eventually show up at a Chicago church. His credit cards had been used at gas stations along the way.
But Raymond Power had no identification, and no idea who he was.
"Basically, it was like I didn't exist," he says now.
Power wound up living as a homeless man in Chicago, staying at a shelter called the Pacific Gardens Mission. He could remember nothing of his former existence except a semblance of his name: Jay Tower.
Then, a friend at the shelter saw a missing persons report on the Web site for "America's Most Wanted." It was Power.
"He was in good shape physically," said Phil Kwaitkowski, vice president of ministries at the shelter. "But he was very disoriented and very confused because he didn't know his identity. At one point he broke down and began to cry on the shoulder of one of our security guards because he was so frustrated that he didn't know who he was."
Power maintains he asked authorities for help, even the FBI, but to no avail.
"It just broke my heart," said Arthur Johnson, who had befriended Power. "I couldn't really understand his situation. But I sympathized for him."
Power's wife, Jane, was able to talk to her husband by phone, but he was not able to remember her or their children.
"We will … get him the treatment he needs," Jane Power said, "so he'll be a part of our family again."
"We're trying to be patient and let the doctors run their course and do what they need to do," added Susan Power on "Good Morning America."
There have been cases of 'mystery men' who turned out to be frauds. Most recently, England's so-called 'piano man,' who was found wandering a beach and enchanting people with his piano playing, was exposed.
Despite a fair amount of skepticism regarding people who disappear claiming amnesia, Raymond's sister is sure her brother didn't skip town to reinvent himself.
"He has tried to find a solution to this amnesia by going to the hospital," she said. "He's had his fingerprints sent to the FBI, he's been trying to find out who he is to get out of the shelter. And he couldn't do that because he didn't know his date of birth and couldn't get any I.D."
Doctors don't know what caused Power's amnesia. But there are clues as to what may have led the lawyer, who was also a churchgoer and Boy Scout leader, to suddenly forget his entire life.
Doctors say some rare cases of amnesia can result from extreme stress and typically affect patients who have had post-traumatic stress disorder.
Power was haunted by the memories of the friends he lost while fighting in Vietnam. The psychological pain was dredged up after a narrow escape from the terrorist attacks of Sept. 11.
His family says he often wondered why he chose to leave his office at 7 World Trade early on the morning of the attacks. He was walking between the twin towers minutes before they were attacked.
Power has overcome a lot of adversity in his life -- he was a police sergeant who found time to put himself through Fordham Law School. But reacquainting himself with a family and world he has no recollection of may be his most difficult challenge yet.
All Power's family knows is the husband of 30 years is finally back home with the family that feared he could be gone forever.
"I think his family is just so delighted to have him back," Susan Power said, "and just focusing on the future and having the time and the privacy to just get their lives together."
ABC News' Gigi Stone, Ron Corning and David Muir contributed to this report.