SAN FRANCISCO -- In what was being treated as a possible break in the 1984 disappearance of 10-year-old Kevin Collins, police on Tuesday searched a home in San Francisco's Haight-Ashbury neighborhood, a block from where he last was seen, and recovered bones that were sent to a state crime lab for testing.

San Francisco police, who were heading the investigation with assistance from the FBI and Alameda County Sheriff's Office, cautioned that preliminary analysis suggested the bones dug up from under the home's garage appeared to be those of an animal.

San Francisco police also stressed that the home's current occupant is not a suspect. But police considered a previous owner, whom they did not identify, a "person of interest" in Collins' disappearance.

During the search, police cordoned off much of the 1100 block of Masonic Avenue near Page Street. The search warrant affidavit, they said, was sealed. Police initially told reporters a cadaver-sniffing dog had detected possible human remains under the concrete of a garage on the block. After digging up the concrete, police sent bones to the San Francisco medical examiner's office for analysis, they said.

Collins' mother, Ann Collins, said police had called to inform her there was a possible break in the case, and that some bones were sent to a lab for testing. But beyond that, she said police haven't told her much else.

"This is fairly unusual," Collins told this newspaper. "There just haven't been leads for years and years and years."

Residents in the buildings closest to the garage where police recovered the bones said police told them they were conducting a homicide investigation.

Emma Larson, who lives at 1112 Masonic Ave., said police asked to use the window of her apartment to survey the yard below. "It was scary," she said.

Another student, Arthur Wentworth of Texas, heard banging around and thought it was a training exercise.

Kevin, a fourth-grader at St. Agnes School in the Haight-Ashbury district, last was seen Feb. 10, 1984, shortly before 8 p.m., waiting for a bus at the corner of Oak Street and Masonic Avenue after leaving basketball practice at the school gymnasium.

Kevin Collins' disappearance sparked a national search effort and was among the first to raise widespread public awareness of child abductions. Flyers with Collins' iconic picture -- a freckle-faced boy looking over his shoulder after writing his name in chalk on a board -- were posted throughout the city. His photo also appeared on milk cartons and billboards, and was featured on the cover of Newsweek in a an article entitled "Stolen Children."

Mike Saba, who grew up in the neighborhood and went to the same school as Kevin Collins, told this newspaper that word of the possible break in the case "just makes the hair stand up on the back of my neck."

He recalled that his father pulled him out of St. Agnes after Kevin went missing.

"It changed everything," Saba recalled. "We couldn't walk home, we couldn't do nothing. It really struck a nerve."

Saba added that he hoped police had finally solved the case and that "they brought him home."

"Everyone deserves to be home," Saba said.

Kevin Collins was one of nine children of Ann and David Collins. They have since divorced. Following Kevin's disappearance, David Collins established the Kevin Collins Foundation for Missing Children in San Francisco to raise awareness and help develop leads on abducted kids like Kevin. But he folded the foundation 12 years later, citing lack of funding. By the mid-1990s, Collins' foundation was competing with other nonprofits devoted to the cause of missing children, including the Polly Klaas Foundation.

Collins' family has long assumed he was murdered. In 1994, on the 10th anniversary of his disappearance, the family held a private memorial service for Kevin, dedicating a bench to him at Holy Cross Cemetery in San Francisco.

"The whole family had decided he was gone," Ann Collins said.

But news of a possible break had brought a flurry of phone calls among Kevin's now grown brothers and sisters, their mother said.

Ann Collins said that after all these years, she has mixed emotions about the possible break in Kevin's disappearance.

"I'm so numb, I don't know what to think," Collins told this newspaper. "Part of me wishes for it to be over. And part of me doesn't."

Bay Area News Group reporter Karl Mondon contributed to this report. Contact Katie Nelson at 925-945-4780 or follow her at Twitter.com/katienelson210. Contact John Woolfolk at 408-975-9346. Follow him on Twitter at Twitter.com/johnwoolfolk1.