Henry County Sheriff Frank Cassell said Saturday the police believed they were looking for one person or several people known to the family in the case of missing 9-year-old Jennifer Renee Short.

Jennifer disappeared Thursday after her parents were shot to death in their western Virginia home.

Cassell said police believe the crime was committed "by someone who knew this family and knew their way around." He gave few details, saying there were no suspects but that at least one new search warrant would be requested.

The man who found her father's body, a laborer who had worked for Michael Short's mobile home moving business, was questioned and released the day of the slayings, police said.

Police say the man also was the last person to see Michael and Mary Short alive, at about midnight on Wednesday.

Cassell said police have interviewed dozens of people, including Michael Short's son from a previous marriage, but it has been difficult locating many of Short's former employees.

"It was a very labor-intensive business," he said. "He hired a lot of different short-term people. A lot of them are transient."

Volunteers combing the area's rolling hills for signs of Jennifer found no evidence and ended their search Saturday, officials said.

Two days of scouring the rural area near the family's home on foot, with all-terrain vehicles and in cars found no traces of her, said Richard Cox, head of the Old Dominion Search and Rescue team.

"Frankly, we need to keep looking," a weary Cox said Saturday as he strained to hold back tears. "But realistically and logically, putting all the evidence together over the past couple days, we don't have a direction to look in."

Police believe Jennifer was abducted early Thursday morning when her parents were each shot once in the head. Police were notified after the co-worker of Michael Short, 50, found his body in an enclosed carport around 9 a.m.

Henry County Sheriff's deputies later found the body of Mary Short, 36, in the bedroom. No weapon was found and there was no sign of their daughter; authorities quickly ruled out the possibility that Jennifer shot her parents and ran away.

At an evening briefing, Cassell said police believe Jennifer was taken from her bed.

Police initially thought Jennifer hid in the hills behind the home during the shootings, but when she didn't turn up, authorities issued an Amber Alert, transmitting information about the missing child to law enforcement agencies and media across the country.

A team of trained volunteers and about 150 area residents searched the area around the clock since the alert was issued.

State police were continuing their search of a 20- to 50-mile radius around the Shorts' home Saturday, assisted by sheriff's deputies from several counties and at least four FBI agents, Cassell said.

The Shorts had recently put their home up for sale, and Cassell said they were checking people who had been by to look at it.

As the search for her granddaughter stretched into its third day, Margaret Hall stayed close to the radio and television at her home in the hills above Callaway, Va., about 30 miles from where her daughter and son-in-law lived. Hall, 71, remembered when she last saw her daughter and granddaughter at a family cookout two weeks ago.

"She was my baby one. She will always be my baby," Hall said.

Elmer Hall, Mary Hall's brother, said the Shorts had no known enemies, no major debts and that authorities told him his brother-in-law still had $60 in his wallet when he was found.

"It wasn't a robbery," he said.

The Associated Press contributed to this report.