He had grown a goatee and dyed his brown hair an unlikely shade of reddish-blond. But there was no disguising the smug self-confidence that seemed such a large part of Scott Peterson's personality. Heading into the upscale Torrey Pines Golf Course near San Diego on Good Friday morning, Peterson paused to give a jaunty wave to the police officers he had spotted tailing him. Seconds later his smile vanished as a posse of a half dozen cops pounced and bundled him handcuffed into a waiting car. Throughout the 12-hour drive back to his hometown of Modesto, the normally affable Scott said nothing, staring off in the distance as the evening darkness closed in around him.

Silence may be a sensible option; Peterson, 30, certainly has much to answer for. A few hours after his arrest, authorities announced they had identified the bodies of a woman and child who had washed up near the Berkeley Marina in San Francisco Bay as those of Peterson's pregnant wife, Laci, 27, and their unborn child, who was to have been named Conner. That discovery, close to where Scott said he had gone fishing on Christmas Eve, the day Laci vanished, was only the crowning clue in a case that the authorities touted as virtually airtight. "I would call the odds slam dunk that he is going to be convicted," proclaimed California attorney general Bill Lockyer. For Laci's family the sudden turn of events brought at least some relief after four months of uncertainty. "I love my daughter so much. I miss her every minute of every day," a weeping Sharon Rocha, Laci's mom, said at an emotional press conference on April 21. "My heart aches for her and Conner."

For months investigators had gone out of their way to insist publicly that Scott had not been ruled in or out as a suspect. But by the time the remains of Laci and the baby were found, authorities had Peterson, a fertilizer salesman, under near continuous surveillance, using wiretaps, vehicle tracking devices and teams of agents. Investigators indicated that they finally arrested him out of fear he might flee. Aside from his altered appearance, at the time he was picked up he was also reportedly carrying $10,000 in cash and an ID belonging to one of his brothers and was within 30 miles of the Mexican border.

There is much about this horrific crime that remains in the hands of forensics experts, and prosecutors are keeping a tight lid on the evidence against Peterson, who pleaded not guilty at his arraignment. It is not even clear whether they have an idea how Laci, who had worked as a substitute teacher, and the baby were murdered. The bodies were badly decomposed – authorities did not deny reports that Laci's body was missing the head – and were identified through DNA testing. As to how the baby came to be expelled from the womb: one possible, and grisly, explanation is the phenomenon of "coffin birth," in which the buildup of gases in the mother's decaying flesh forces a postmortem delivery. Whatever the means, authorities allege that the murders were committed at the Petersons' home in Modesto sometime between the evening of Dec. 23 and Christmas Eve morning. As it happens, a neighbor later reported seeing Scott load something wrapped in a blue tarp into his boat, which was backed up into the driveway, on Christmas Eve day. When questioned, Scott told police he had been taking some backyard umbrellas to his warehouse for storage. The day after Laci's body was found, a black plastic sheet, 42 in. wide and nearly 20 ft. long, washed up in the same area, though investigators do not yet know if it is related to the crime.