A man suspected in the disappearance his two children, who authorities now fear are dead, had told his ex-wife that he would not abide by a new custody arrangement, his ex-wife said in court records.

Authorities say accountant Manuel Gehring (search), 44, drove across the country starting July 4 or 5, possibly with his children. Court records say 14-year-old Sarah and 11-year-old Philip were in tears when they were last seen with their father leaving a July 4 fireworks show in Concord.

FBI agents and officials searched for the children Sunday without success and again Monday at points along Gehring's route between Concord and Gilroy, Calif., where Gehring was arrested Thursday.

New Hampshire Attorney General Peter Heed (searchdeclined to release further details Monday about the search, but in a brief interview he said he held out little hope that Sarah and Philip would be found alive.

"Until we find bodies, you never say never. But based on everything we know, our level of confidence that they are dead is very high," he said.

Prosecutors have said Gehring is the sole focus of the investigation.

Gehring waived extradition Monday during a hearing in San Jose, Calif., and authorities said they expected him back in New Hampshire on Tuesday. He was arrested on charges of interfering with custody.

Charlie Gillan, a public defender who met with Gehring for three hours before his hearing, said his client was somber and depressed, but lucid.

"He didn't break down and become hysterical," Gillan said. "He seemed to be able to understand what I was talking about."

Authorities have disclosed few facts about the case, and a judge granted a request by attorneys that Gehring's arrest warrant remain sealed.

A naturalized citizen from Nicaragua (search), Gehring was out of work after finishing an 18-month contract job with a Nashua firm last month, according to a petition for emergency custody of the children filed by his ex-wife, Teresa Knight, on July 7.

Gehring and Knight signed a mediated agreement on June 24 -- the day they were supposed to go to trial over custody -- that said Sarah and Philip would go to school in Concord, where their father lived, but would spend two or three days and nights each week with their mother in Hillsboro.

After signing the agreement, Gehring "called (Knight) and advised her that he had no intention of following the agreement," according to her July 7 petition in Merrimack County Superior Court in Concord. Gehring "was very agitated and angry in his last telephone call with (Knight)."

A woman who considered Gehring her closest friend and spoke to him every day said he was thrilled when Knight signed the agreement allowing Philip to go to school in Concord and spend about 60 percent of his time at his father's.

"He really like being around the kids," Linda DeSantis told the Concord Monitor.

The focus of the search for the children is the Midwest, according to Assistant New Hampshire Attorney General Jeff Strelzin.

FBI Special Agent Robert Hawk in Cleveland said information that he would not disclose prompted a seven-hour search Sunday near Toledo, Ohio. FBI agents and police searched on foot and in a helicopter in open areas and parks along major highways and thoroughfares but did not find the children.

Officials said unspecified evidence found Friday night and early Saturday led them to believe the children are dead. Strelzin would not discuss the evidence or say whether Gehring was helping them find the children.

Gehring was being held in the mental health unit of the Santa Clara (Calif.) County jail. A jail spokesman said Gehring is depressed but was not considered a suicide risk.

Teresa Knight, who is four months pregnant with twins, has not spoken to reporters, but her husband, James Knight, the children's stepfather, told the Monitor they were struggling to cope with the news.

He said they last saw the children on July 2 when they dropped Philip off at his father's home.

"There were no problems as we saw them," he said.