Scott Peterson's (search) mother took the witness stand Monday to defend her son and help explain away behavior police have described as that of a guilty man.

His lawyer, Mark Geragos (search), first sought to explain why Peterson was carrying nearly $15,000 in cash when he was arrested in San Diego (search) — a detail prosecutors have suggested meant he was preparing to flee.

Jackie Peterson, with a small oxygen tank slung over her shoulder and tubes running into her nose, spoke softly, her voice often breaking. She suffers from a lung ailment.

She explained that she had inadvertently withdrawn $10,000 from a bank account that bore both her name and Scott Peterson's, in order to loan another son some money.

Jackie Peterson said on April 17, a day before Scott Peterson's arrest, she gave him back the $10,000 she accidentally withdrew from his account.

Jackie Peterson then described a trip to the seaside town of Carmel with her son and his wife, Laci, the week before she vanished. She said that while Scott Peterson and his father played golf, the women walked around town.

"And Laci, six days before she went missing, was able to walk down to the beach, she was able to walk into town, she was able to walk around with you for hours?" Geragos asked.

"Yes," Jackie Peterson said.

Defense attorneys are trying to counter prosecution claims that Laci had stopped walking long before she vanished as her pregnancy crept into its eighth month.

Prosecutors allege Peterson killed Laci on or around Dec. 24, 2002, then dumped her body into San Francisco Bay. The remains of Laci Peterson and her fetus washed ashore about four months later, a few miles from where Peterson claims to have been fishing alone the day his wife vanished.

Defense lawyers claim someone else abducted and killed Laci while she walked the couple's dog.

On cross-examination, prosecutor Rick Distaso said it was odd that Peterson purchased a used Mercedes using his mother's name.

Jackie Peterson replied that she told Scott to buy the car in her name because police periodically impounded Peterson's vehicles to search for evidence — at the same time secretly installing GPS tracking devices.

Later, Peterson's father, Lee, testified that he had planned to play golf with his three sons, including Scott, on April 18, 2003. It was the same day police were working to identify the bodies of Laci and the fetus found days earlier.

"I was going to get three of my sons together to play golf and just look for some normalcy in our lives," Lee Peterson said.

Scott Peterson never joined the group. He was arrested that morning after the bodies were identified.

Along with the cash found in Peterson's car, police discovered camping equipment, several changes of clothes, four cell phones, and two driver's licenses — his and his brother's, another detail prosecutors have suggested pointed to Peterson's intent to flee.

But Lee Peterson explained that he told Scott Peterson to get his brother's license the day before in order to get a San Diego resident's discount at the golf course.

"Because I'm cheap," Lee Peterson explained.

Lee Peterson later added that his son was "living like a nomad out of his car" because of all the media attention.

Earlier Monday, an investigator testified that Laci Peterson's mother said her slain daughter informed her she was pregnant on June 9, 2002.

The testimony by Modesto Detective Craig Grogan was presented by the defense to bolster the assertion by an expert last week that Laci Peterson's fetus was still alive days after the eight-months-pregnant woman vanished just before Christmas 2002.

The expert witness, Dr. Charles March, had come under heavy attack from prosecutors when he testified that the fetus probably died on Dec. 29, 2002, at the earliest.

The defense case was expected to conclude as early as Tuesday. Closing arguments are tentatively set for Nov. 1-2.