Deadly bond:

WASHINGTON -- A lot of criminals had fathers who were never there for them. John Allen Muhammad was there for the teenager John Lee Malvo, fussing over his diet, directing him closely, acquaintances said, as a strict parent might do.

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Theirs was a deadly bond, authorities believe.

Among all the possibilities mentioned by the multitude of crime historians and profilers and serial-murder scholars as to who might be behind the sniper assaults in the Washington area, a hit team made up of an adult and a teenage companion was never on the list.

Experts thought police were looking for a lone white gunman or perhaps a pair of well-trained killers, maybe even a terrorist or two. Many predicted it would all end with a bloody gunfight or a police sniper taking out the suburban sniper, if they got anyone at all.

Instead police found an Army veteran and a 17-year-old, both black, sleeping in a car at an interstate highway rest stop.

A senior law enforcement source, speaking on condition of anonymity, said police believe Malvo became an informal stepson to Muhammad because the older man had a relationship with the boy's mother, and for a time the three lived in a family type arrangement.

"The boy eventually latched onto Muhammad," the source said. "We don't have evidence it was formalized but it was almost like an informal or common-law stepson."

Muhammad was a controlling figure, not only to his alleged sniper partner but to his own four children, family members and other intimates said. They said he demanded they eat only certain things, and when his children from two ex-wives visited him, he did not willingly return them.

As in routine life, so too, perhaps, in crime.

When people kill in pairs, "there's always one person who runs the show," said Eric Hickey, a professor of criminal psychology at California State University-Fresno and an expert on serial killers. But much about the relationship between Muhammad and Malvo remains unknown.

Sheron Norman, a former sister-in-law of Muhammad, said he introduced Malvo as his son when they came to Baton Rouge, La., in July for a three-day visit.

"You could tell he was scared," Norman said of Malvo. "He was very, very quiet. You could tell he didn't like the way he was living." She said he called Muhammad "father."

Norman's sister, Carol Williams, was Muhammad's first wife. She said she once had to fight a legal battle to get her son back when he was visiting his father in Tacoma, Wash.

Another ex-wife, formerly Mildred Denise Williams, charged in divorce papers that Muhammad had engaged in "physical, sexual or a pattern of emotional abuse of a child" and asked a judge to limit any visitation with the couple's three children. "I am afraid of John," she said.

Little is known about Muhammad's childhood in Louisiana.

Hickey said if there is anything that the diverse portfolio of serial killers shares, it is a troubled youth.

"Often it's emotional abuse," he said. "The rejection and abandonment issues can be much more devastating than anything physical. You always find that the vast majority, if not all, of these serial killers were truly victimized first, and as adults became predators."

He estimates that one in four serial killers works in a team. The largest portion, however, are white male loners.

Few mass-murderers outside the Mafia or the drug trade are joined by family.

Muhammad and Malvo appeared to stick together. They stayed at a homeless shelter in Bellingham, Wash., according to a published report, as well as visiting relatives.

D. Charles Williams, a family psychologist in Dunwoody, Ga., and author of a book on fathers and sons, said Muhammad and Malvo appeared to be in a "mentoring relationship gone bad."