SAN DIEGO — A tow truck driver testified Thursday that he heard an unidentified voice near David Westerfield's secluded campsite the day after 7-year-old Danielle van Dam went missing.

"I thought I heard someone say something," said Dan Conklin who helped Westerfield pull his motor home from a dune outside the desert outpost of Glamis.

"Did you think you two were alone?" asked prosecutor Jeff Dusek.

"Yes," said Conklin.

The driver said that when he asked Westerfield if he had said something, "he responded either 'I didn't say anything' or 'I wasn't talking to you.' I can't remember which."

With his testimony and that of several other witnesses Thursday, the prosecution suggested Westerfield kept Danielle in his RV for some time after her abduction the night of Feb. 1. Searchers found her naked body by a roadside Feb. 27.

Westerfield, a 50-year-old engineer who lived two doors from the van Dams, maintains he had nothing to do with her murder. He told police in two separate interviews that he spent the days after she vanished meandering alone through southern California in his RV.

Westerfield said some of that roaming was a search for his misplaced wallet, but a park volunteer contradicted that assertion Thursday.

Donald Raymond, a retired superintendent who volunteered at the Silver Strand State Beach Park last winter, said Westerfield had his wallet Saturday Feb. 1 when he came to the office of the park campgrounds.

A ranger had refunded Westerfield $30 after determining he overpaid a camping fee, but Westerfield insisted the ranger was wrong.

"After being quite agitated about it, he pulled out his wallet and showed me three or four $20 bills," said Raymond.

"I've never had anyone be agitated about getting too much money back," he said.

Others at the beach campground testified that Westerfield behaved strangely. Joyce Rodgers, who was in a nearby RV, said his motor home pulled into the parking lot Saturday morning between 10 and 11 a.m. with all its curtains drawn.

"Everyone we know that drives a motor home leaves them open, you know, for a better view of changing lanes," said Rodgers.

She and another camper, Beverly Askey, testified that as soon as the RV parked, Westerfield closed the curtain on the front dashboard, completely sealing off the vehicle's interior from view.

It was so unusual, Rodgers said, that she and her son-in-law began discussing "why did the front window get closed? Maybe he had a girlfriend. Maybe he had just been traveling and needed to rest."

While others biked and strolled in the bright sun, Westerfield remained in his RV. Askey and other motor home owners who testified said campers normally set up their sites by spreading a carpet, rolling out the awning and fixing jacks to the vehicle to prevent rocking. Westerfield, they said, did none of that.

Westerfield told investigators he stayed only a short time at the beach because the weather was bad. Defense lawyer Steven Feldman pressed both women about conditions at the water.

"It was beautiful. It was sunny. Cool, but sunny," said Askey's daughter, Teresa Hastings.

Park ranger Brian Neill, who initially returned the $30 to Westerfield, said the defendant did not immediately answer a knock on his RV door. Neill said Westerfield denied overpaying, but took the money. He did not go back into the vehicle until the ranger left, Neill said.

"He didn't move until you moved," asked Dusek.

"Yes, sir," said Neill.

But when Feldman asked the ranger if Westerfield "appeared to be concealing anything at all," he answered no.

The defense lawyer also grilled tow truck driver Conklin about Westerfield's conduct. Conklin said Westerfield seemed to be in a hurry and even rushed off without taking some wood blocks he apparently used as jacks. But, Conklin conceded, Westerfield was "more put-out than nervous."

The driver drew chuckles from the jury when he explained why he had refused to cooperate with a defense investigator. Westerfield, he said, still owed him $70 for towing him.

"They're getting paid," he said of the defense team. "And I'm not getting paid. I said, Pay me and I'll talk to you."

Jurors also heard Thursday morning about calls made to and from Westerfield's cellular phone the weekend of the abduction. According to records presented by Verizon Wireless representative Greg Sheets, Westerfield's phone placed seven calls, received two voice mail messages and checked voice mail twice. Other prosecution witnesses are expected to identify who Westerfield called, but Feldman suggested some of the calls were to his 18-year-old son, Neil.

Westerfield told police he returned to the Silver Strand between 7:10 and 7:30 p.m. Sunday night. Sheets read jurors records showing that a call from his phone at 7:33 p.m. traveled through a cell tower in Mira Mesa, 22 miles from the beach. According to Sheets, calls are routed through the tower closest to the caller's location. If there is congestion, the calls are bounced to the next closest tower.

The towers that relayed the rest of Westerfield's calls that weekend appeared consistent with his account of traveling to the desert in between trips to the beach.