Scott Peterson (search) strangled or smothered his pregnant wife not simply to be with his lover, but to rid himself of an unwanted child and to pursue life as a freewheeling bachelor, a prosecutor contended Monday during closing arguments.

"The reason he killed Laci Peterson (search) was Conner Peterson was on the way," prosecutor Rick Distaso told jurors. "Things were going to change. No more of this running around, living this double-life thing.

"He wants to live the rich, successful, freewheeling bachelor life. He can't do that when he's paying child support, alimony and everything else," the prosecutor said. "He didn't want to be tied to this kid the rest of his life. He didn't want to be tied to Laci for the rest of his life. So he killed her."

The defense was to begin its closing arguments Tuesday, with jurors expected to begin deliberations as early as Wednesday. The trial is in its 23rd week after testimony from 184 witnesses.

Peterson is charged with two counts of murder in the deaths of his wife, Laci, and the fetus she carried. Prosecutors claim he killed her on or around Christmas Eve 2002, then dumped her weighted body into San Francisco Bay. The remains of Laci Peterson and her fetus were discovered along a shoreline about four months later, a few miles from where Scott Peterson claims to have gone fishing alone the day his wife vanished.

Defense lawyers claim someone else abducted and killed Laci.

Prosecutors have claimed Peterson's main motive for murder was to be with his lover, massage therapist Amber Frey (search). On Monday, Distaso elaborated on that theme.

"Amber Frey represented to him freedom. Freedom is what he wanted," Distaso told jurors.

The prosecutor highlighted the "two lives" of Scott Peterson — the public man who appeared to have had the perfect marriage, grieving for his missing wife, and the private man who continued to woo his lover and lie to friends and family even as police searched for Laci.

Distaso began with a home video of Laci with a friend in the couple's kitchen, smiling and waving to the camera.

He then moved to an aerial photograph of San Francisco Bay, pointing with a laser to the rocky beach where the bodies were found, and the area nearby where Scott Peterson says he was fishing the morning Laci vanished.

"The only person that we know without any doubt that was in the exact location in the exact spot where Laci and Conner washed ashore ... is sitting right there," Distaso said. "That alone is proof beyond a reasonable doubt in this case."

Distaso flashed a photograph of a smiling Laci and Scott, then cut to a split-screen image, with one side showing Laci sitting alone at a Christmas party, eight months pregnant, the other showing Scott and Frey embracing at a different party that same night.

Weeks before Laci disappeared, Peterson told the woman who introduced him to Frey, "I was once with a woman who I thought was my soul mate, but I lost her," Distaso said.

"Laci Peterson was dead to Scott Peterson a long time before he killed her," Distaso said. Some jurors nodded and scribbled notes as he spoke.

When he got home from fishing, Peterson told neighbors that he had been golfing all morning. He would repeat that story to one of Laci's relatives before telling police he had actually been fishing.

"I don't care how upset you are ... nobody forgets that you just got home from fishing at the Berkeley Marina," Distaso said.

Peterson had planned to dump Laci's body, get back to Modesto and go to the golf club, Distaso argued, but the disposal took longer than planned.

"And that was it. He just screwed it up, screwed up his alibi," Distaso said.

Peterson's lawyers claim whoever abducted Laci Peterson deliberately left her body where Scott Peterson was fishing to frame him. Distaso disputed that.

"Here's how you know without any doubt that that's not true. What possible reason would there be to weight down or even hide the bodies ... if you're going to pin it on somebody?" Distaso said.

"That man's a murderer," he added. "There's no mystery in this case."