Sitting in his lawyer's office last month, real estate developer Andrew Kissel couldn't hide that he was in a world of trouble. "I looked in his eyes and saw someone who was nervous," says attorney Howard Graber. Given that Kissel had agreed to plead guilty to a series of swindles, was probably headed to prison for at least five years and was in the middle of an especially nasty divorce, his jumpiness, Graber thought, was not inappropriate. Two weeks later, Kissel, 46, was found gruesomely murdered in the basement of his Greenwich, Conn., mansion. Graber again recalled their last meeting: "Maybe he was nervous because he was looking over his shoulder, waiting to get whacked."

At this point, the only thing certain is that Kissel's murder was as brutal as it is mysterious. The victim had been stabbed four or five times in the back. His hands and feet had been bound with plastic restraints. According to Andrew's father, William, who has been briefed by police, investigators found no sign of forced entry at the mansion, where Andrew had been staying alone, nor any fingerprints that didn't belong there. There were no defensive wounds on Kissel's hands, suggesting the lack of a struggle. "Whoever killed him, it wasn't a little guy," says William, a retired chemist and inventor. "My son was very strong." He also had a long career as a very shady businessman and a long list of enemies. "He led a complex life," his criminal defense lawyer Philip Russell says drily. "Many people were unhappy with him."

For starters, there were several banks that federal prosecutors, in a case brought against him last June, say he bilked out of $20 million by applying for loans with phony documentation. Then there were the members of his Manhattan co-op, who discovered in 2003 that Kissel, who served as the treasurer of the building, had embezzled more than $4 million from them after they gave their smooth-talking neighbor wide control over the finances. Kissel used his ill-gotten money to help fund a decidedly upscale life, which included a $3.4 million yacht and a private jet. Kissel was also being sued by his business partner in a Connecticut real estate development firm for stealing assets. As an added twist, Andrew is the brother of Robert Kissel, a prominent banker living in Hong Kong who was killed by his wife, Nancy, in 2003 in the notorious "milk shake murder" (see box). Says Lt. Daniel Allen of the Greenwich police, who are heading the current investigation: "The officers have a lot of work ahead of them, a lot of people to talk to."

Perhaps the most bizarre possibility is that Kissel, facing jail and with his life in financial ruin, had hired a hit man to have himself killed, so that his daughters, Ruth, 8, and Dara, 6, might inherit the money from his insurance policy. That scenario first cropped up in an article in the New York Post, which quoted an unnamed "source familiar with the case" floating the possibility. When asked, police would not confirm or deny if they are in fact pursuing that angle. Kissel's father says he initially considered the suicide-by-hit-man possibility "preposterous" but now isn't willing to rule it out. "I changed my mind," says William, mournfully and on the edge of exhaustion. He adds that it is his understanding that his son did have an insurance policy worth between $10 million and $15 million: "He loved his children, and he wanted them to get something from this, so that's a real possibility."

In contrast to his turbulent end, Andrew Kissel grew up in comfort and stability. His father invented a process for copy machine toner that enabled the family to live in ritzy Saddle River, N.J. "His parents were great people," says Danny Williams, 42, Robert Kissel's childhood best friend. Even as a youngster, though, Andrew was troubled. "As we got older, Andy started hanging out with a bad crowd," recalls Williams. "He started smoking pot, doing cocaine. I once saw him steal money out of his mother's purse." In that respect, says Williams, he was "totally different" from younger brother Robert, who was down-to-earth and didn't cut ethical corners. "Andrew always wanted to have the best car and the best tires on it," says Williams. "I think he was just greedy. He wanted it all and didn't want to have to work hard for it."

All the same, there are reasons to doubt the suicide-by-hit-man scenario. Kissel's attorney Graber points out that the method of death—stabbing—was especially painful. "I don't think that's the way Mr. Kissel wanted to go out," says Graber, who was handling Kissel's divorce. "Maybe a bullet to the back of the head if he was that slick about arranging his death." Vernon Geberth, a retired New York City homicide commander and the author of Practical Homicide Investigation: Tactics, Procedures and Forensic Techniques, a textbook used in police academies all over the country, agrees. "That's ludicrous," says Geberth. "If you're going to have yourself whacked, you don't submit yourself to being bound and stabbed." But to Geberth's practiced eye, the method of murder does suggest some other lines of inquiry. "Multiple stabbing connotes to me anger and/or rage," he says. "The binding is an element of torture, so I would be leaning more toward a personal motivation than strictly a hit."

At the time of his murder, Kissel's divorce from wife Hayley, 43, had become more heated. She had filed a motion to have him evicted from the house. The day before he was last seen alive, Saturday, April 1, he and Hayley, a former champion skier whom he met when she was the ski instructor for Andrew's sister Jane, openly quarreled in front of the moving men who were there to pack him up. (It was the movers, returning on Monday, who discovered the body.) But Graber, for one, is certain that the divorce, though somewhat acrimonious, had nothing to do with his client's death. "When he sat with me in my office, he didn't seem as bitter and filled with hate as 99 percent of the people who sit here," says Graber. (Police have said that Hayley is fully cooperating in the investigation.)

In the end, of course, for all his scheming ambition, Andrew, who suffered from substance abuse and was taking antipsychotic medicine for bipolar disorder, got nothing but a squalid death. Only about 20 people attended his funeral. Among the no-shows were his wife and kids, kept away by a feud that has raged in the family ever since Andrew and Hayley fought unsuccessfully to get custody of Robert's three children after his murder. (The kids are now living with Robert and Andrew's sister Jane.) Even for his defense lawyer, the whole strange saga remains an enigma that may or may not be solved. Says Philip Russell: "It is a true mystery."