Mark Geragos said in closing arguments that the evidence shows Peterson did not murder his wife, Laci, and the fetus she carried, and that he had no motive to do so.
Geragos suggested that the prosecutors had made the jury hate his client. But he added: "You're not supposed to just decide this case on whether or not you like Scott Peterson."
Geragos then accused authorities of waffling on their theory of the crime, first claiming Peterson's affair with massage therapist Amber Frey was his motive for murder, then raising financial issues and finally pointing to Peterson's desire to be free from marriage.
"Clearly Amber was not the motive. Nobody was going to kill Laci Peterson and her child for Amber Frey," Geragos said.
The jurors heard the prosecution's closing argument Monday and are expected to begin deliberations as early as Wednesday. The trial began with jury selection in March and opening statements in June.
Prosecutors claim Peterson strangled or smothered his wife on Dec. 23 or 24, 2002, then dumped her weighted body into San Francisco Bay. Defense lawyers claim someone else abducted and killed Laci.
Peterson is charged with two counts of first-degree murder and could get the death penalty. The jury will also be allowed to consider second-degree murder, which does not require evidence of premeditation and carries 15 years to life in prison.
Peterson's parents and siblings, and Laci's mother, stepfather, and siblings have been in the courthouse throughout the long trial.
After listening to the prosecution sum up Monday, and then Geragos' closing statement, Susan Padillo - Scott Peterson's sister - said she believes he will be acquitted.
"I see that it's very clear," said Padillo. "I'm confident the jury will see it as clearly, and we'll be out of here very soon."
The prosecution closing statement Monday began with home video of Laci Peterson, happy and very much alive. Then District Attorney Rick Distaso showed a picture of Laci pregnant and smiling alongside a photo of her decomposing remains.
The jury's reaction was "huge," said CBS News Early Show Legal Analyst Trent Copeland. "This jury was visibly moved."
"He raised tears in the eyes of that jury and he impressed them with the fact this murder case this is about the death of a real vivid, vivacious human being," said legal analyst Dean Johnson.
With just a day to summarize their case against Scott Peterson, prosecutors painted a picture of a man so desperate for freedom from domestic drudgery that he turned to murder as his only way out.
The prosecution closing argument also made a case for premeditation, contending that each bit of evidence is like a piece of a puzzle that convicts the former fertilizer salesman.
Geragos, speaking for the defense Tuesday, said pieces are missing in that puzzle, such as the fact that Peterson paid a bill for Laci's health insurance the day before she vanished.
In addition, he said, "Maybe the logical explanation for the fact that we have no evidence of her struggling in that house, dying in that house is because it didn't happen in that house."
Also, Geragos said police found that someone had used a computer in the Petersons' home on the morning Laci vanished - after authorities contend Peterson had already killed Laci - to search Web sites for a fleece scarf and a sunflower-motif umbrella stand.
He suggested the user was actually Laci because the schoolteacher had a tattoo of a sunflower on her ankle.
Geragos said police never tried to determine who the computer user was "because they didn't want to know the answer."
He also tried to cast doubt on prosecutors' contention that Peterson had a financial motive for the killing, noting that Laci was set to inherit nearly $1 million.
"And yesterday for the first time you hear a new theory ... that he didn't want to pay child support," he added, noting that payments would have been minimal once Laci received her inheritance.
"She meant more to him alive than dead," Geragos said.