Redwood City, Calif. ? Prosecutors focused Thursday on the clothing Laci Peterson wore the day before she was reported missing as they set out to establish when she died and link her husband to the slaying.

Meanwhile, defense lawyers assailed what they characterize as a botched investigation that culminated in two murder charges against Scott Peterson, a 31-year-old fertilizer salesman.

Prosecutors say Peterson killed his wife, who was eight months pregnant, in their Modesto home on or around Christmas Eve morning 2002, then drove her body to San Francisco Bay and dumped it from his small boat. Lawyers for Peterson, who says he fished in the bay that day, speculate that someone else abducted and killed his wife.

The remains of Laci Peterson and her fetus were badly decomposed when they washed ashore in April 2003, and authorities have not offered physical evidence to pinpoint exactly how or when she and the boy, whom the couple planned to name Conner, were killed.

As a result, prosecutor Rick Distaso spent much of Thursday — the first full day of testimony in the trial — talking about her clothing.

Peterson told police that his wife wore a white shirt and black stretch pants when he left for a solo fishing trip Christmas Eve morning. Prosecutors have said her remains were clad in khaki pants.

Two prosecution witnesses who work at a spa Laci Peterson visited around midday Dec. 23 testified she wore a white shirt and black stretch pants. Two other witnesses, including Laci Peterson’s half-sister, testified she was wearing light-colored pants that evening at a salon.

Those recollections could fit the prosecution’s theory that Peterson killed his wife late Dec. 23 or early Dec. 24 — after she had changed clothes — then disposed of the body after daybreak.

Peterson, 31, faces the death penalty or life without parole if convicted.

Even as prosecutors tried to make their case, Peterson’s attorneys tweaked authorities with assertions of their incompetence.

The owner of Sweet Serenity Day Spa, where Laci Peterson went for a waxing treatment just after noon on Dec. 23, said police inaccurately recorded parts of her initial statement. Michelle Buer said she didn’t tell authorities on the day Laci Peterson vanished that she suspected Scott Peterson was involved — though she did say that later.