The bloody trail keeps lengthening, the what-ifs keep mounting up. By the end of last week, the sniper suspects had been linked by law enforcement to 20 shootings (13 dead, five wounded). Muhammad and Malvo apparently began their spree as far back as Feb. 16 with a shooting in Tacoma, Wash., and shot a woman outside a beauty parlor in Baton Rouge, La., on Sept. 23. In addition to the liquor-store shooting on Sept. 14, NEWSWEEK has learned, police are looking closely at a shooting outside a restaurant in Clinton, Md., on Sept. 5. The restaurant owner, Paul LaRuffa, was shot six times as he sat in his car after closing up at about 10:30 p.m. As LaRuffa lay bleeding and groaning, his assailant reached into the car and grabbed a Sony laptop and a briefcase with $3,500 in cash. Police are checking to see whether the laptop matches the one found in the back seat of the snipers’ Caprice. It may also be significant that the shooting occurred less than a mile from the home of Muhammad’s ex-wife Mildred.

The evidence continues to pile up against the sniper suspects, arrested as they slept in a Maryland rest stop on Oct. 25. But investigators hunting a motive are groping in a psychological maze. At Attorney General John Ashcroft’s Justice Department and the FBI, some officials naturally wondered about terrorism. Ever since the 9-11 attacks, the Feds have worried that Al Qaeda would recruit a fifth column from the ranks of Black Muslim extremists in the United States. Muhammad may have been influenced in some vague way by radical Islam. Authorities believe that he or Malvo may have taken a potshot at a Tacoma synagogue. He has been an occasional admirer of Nation of Islam leader Louis Farrakhan (who has condemned the sniper killings) and in boastful conversation made wild threats to massacre police and government officials. But federal investigators have been unable to tie Muhammad and Malvo to any underground cell or group.

Muhammad’s real demons may be closer to home. The geography of the shooting spree suggests that his obsession with losing his children somehow metastasized into serial homicide. He threatened his second wife Mildred during a bitter custody battle and also abducted the three kids and took them to Antigua for more than a year. When he returned to the United States, Mildred went to local authorities to win back the children; Muhammad, always a dreamer and a con man, appears to have become delusional. Pathetically, he told an old girlfriend that he was back together with his wife, but that she was in Europe and his children were taking ballet lessons. In a case of twisted transference, he virtually adopted young Malvo, a Jamaican boy left alone by his mother on the island of Antigua, where Malvo fell under Muhammad’s sway. They reunited in the United States. With Malvo, whom he trained to fire a rifle and handgun, Muhammad began a violent campaign that seemed random, yet may have circled around his ex-wife and children.

The first intended target may have been a woman he blamed for helping his ex-wife take back the kids. Isa Nichols is a business consultant who worked with John and Mildred Muhammad on a failed truck-and auto-repair service. When Muhammad stole the kids, Nichols took pity on Mildred and gave the cops Muhammad’s license-plate and cell-phone numbers. Using the information, the authorities finally caught up to Muhammad in Bellingham, Wash., in August 2001, and returned the children to Mildred. Muhammad may have wanted to get even. On the night of Feb. 16, Nichols’s niece Keenya Cook was staying at Nichols’s home in Tacoma. Cook had just finished changing her baby when the doorbell rang. She opened the door and was shot in the face. Last week Washington state police linked Muhammad and Malvo to the .45-caliber handgun that killed Cook.

Mildred fled to a town house in Clinton, Md., with the three kids (John Jr., 12, Salena, 10, and Taalibah, 9). But Muhammad apparently followed. Mildred has told police that she never saw or heard from Muhummad during the killing spree, NEWSWEEK has learned. But her brother Charles Green told a reporter, “He was going to kill everyone in my family. He loved the kids, and when he couldn’t see the kids anymore… There’s no doubt that Mildred was going to be the next hit.” Malvo’s role remains unclear, but police confirmed that it was his voice on the tape of a 911 call that was broadcast last week. “We have called you three times trying to set up negotiations,” the voice said. “We’ve gotten no response. People have died.” The police dispatcher told him to call the sniper hot line.