David Westerfield, a self-employed engineer, shook slightly as the verdict was read and blinked repeatedly as he watched the jury. The penalty phase of the trial begins next week and he could be sentenced to death.
The jury of six men and six women found Westerfield guilty of murder, kidnapping and possessing child pornography on the 10th day of deliberations.
Danielle's mother, Brenda van Dam, burst into tears and hugged her husband Damon as they watched from the back row of the court. They remain under a gag order.
One juror appeared to wipe away tears. None of the jurors looked at the defendant. The panel was ordered to return Aug. 28 to begin the penalty phase.
Westerfield supporters were stunned. One unidentified woman wept.
"I am in shock. I am just in shock," said David Neal, a former brother-in-law of Westerfield. "He thought he was going to get off."
Prosecutors said Westerfield slipped into the van Dam's suburban San Diego home and abducted the girl after her father put her to bed Feb. 1. Her badly decomposed body, naked except for the plastic choker necklace she always wore, was found beside a back-country road on Feb. 27.
Westerfield, who lives two houses away from the van Dams, was placed under surveillance early in the investigation after authorities learned he was at the same bar as Danielle's mother and two of her girlfriends the night the girl vanished.
He left on a long, meandering trip in his motor home early the next day as police and volunteers searched the neighborhood. He later retraced his RV trip with police and made the unsolicited comment that "this would be a great place to dump a body," according to court documents.
Drops of the victim's blood were later found on Westerfield's jacket, which prosecutors called a DNA-backed "smoking gun" that jurors couldn't ignore. Investigators said Danielle's blood, hair and fingerprints were also discovered inside the motor home.
CBSNews.com Legal Analyst Andrew Cohen predicts the sentencing phase will be even more emotional than the trial was, "and that's saying something."
"Prosecutors will bring back to the stand Danielle's parents and maybe other family members to tell jurors about the loss they have suffered since her murder," says Cohen. "Westerfield's team, meanwhile, will try to make the case that a life sentence is an appropriate result here."
But, Cohen continues, "It's hard to see Westerfield getting life instead of death now. This is precisely the sort of crime people think about when they think about crimes for which the death penalty may be appropriate, and I'm not sure the fact that Westerfield is a father or that he didn't have a criminal record before this will generate enough sympathy with jurors."
The defense argued that there was no motive and suggested it was improbable that the 6-foot-2 suspect could have slipped into the girl's home in the dark and snatched her away without leaving evidence of his presence.
Defense lawyer Steven Feldman also noted that Danielle and her mother had once been in Westerfield's home for about 15 minutes as the girl sold him Girl Scout cookies, suggesting that's why her hair was found inside.
Feldman repeatedly suggested that someone else was the killer, noting that a fingerprint found in the van Dam home and a hair found on the girl were never identified.
The defense also argued that the lifestyle of Danielle's parents, which included marijuana use and spouse-swapping, exposed their home to people who might have been responsible for the girl's disappearance.
That line of defense enraged the van Dams, their supporters and many in the close-knit community.
The jury began deliberating in the case earlier this month with nearly 200 exhibits and the testimony of 116 witnesses to study.
Danielle's kidnapping preceded other frightening abductions this year, including those of Elizabeth Smart in Utah, Samantha Runnion in Orange County and Cassandra Williamson in Missouri. Smart remains missing; the rest were slain.