WASHINGTON • Army officials under scrutiny for a scandal at Arlington National Cemetery testified Thursday that they have found additional mismarked graves and have opened a criminal investigation into contracts for a failed computer system to track burials.

During a Senate Homeland Security subcommittee hearing, angry senators lectured Army officials and former managers at the cemetery for disclosures that have upset military families and veterans organizations.

Sen. Claire McCaskill, D-Mo., who chairs the panel, called recent revelations 'shocking" and told Army officials that they will be held accountable.

"Bodies accidentally buried in the same graves. Unmarked and mismarked graves. Urns of cremated remains being found in the cemetery's landfill. And the heartbreaking tragedy of the families who now cannot trust the cemetery to tell them where their loved ones are buried," she said.

Sen. Scott Brown of Massachusetts, the panel's ranking Republican, said that the failures "have tarnished the sacred trust with military families ... and eroded the confidence of the families of our fallen heroes have that the remains of their loved ones will be respected."

The former cemetery superintendent and his assistant showed up at the hearing after being subpoenaed. Both were forced to retire after the Army inspector general reported last month that 211 graves were misidentified or had other problems.

Subcommittee investigators said this week that the number of unmarked, mismarked or wrongly mapped graves may exceed 6,000 after a complete survey of the 640-acre cemetery, where the remains of 330,000 individuals are interred.

John Metzler, the superintendent until July 2, said that he wanted to express "my sincere regrets to any family for whom these failures may have caused pain."

But in testimony that often confounded senators, Metzler asserted that he didn't know of problems until recently and claimed that he had been close to getting the computer system up and running when an investigation halted progress.

His testimony left senators shaking their heads.

"This is not complicated," McCaskill said. "It's called keeping track of who you buried where. The notion that you would come in here and act like you didn't know about it until a month ago is offensive. You did know about it and you did nothing."

Brown, a lawyer, remarked: "I'd have a lot of fun with you in a deposition because I don't feel we're getting straight talk here."

Metzler's assistant, Thurman Higginbotham, cited his Fifth Amendment right to avoid self-incrimination in refusing to answer many questions. Higginbotham was in charge of the consultant contracts that failed to produce an automated system to keep track of burial plots. Many were issued without competitive bids.

Higginbotham, who was acting superintendent when Metzler arrived, said he hadn't been permitted to contend for Metzler's job. But he disputed Army reports that a poor working relationship with Metzler contributed to the problems.

The subcommittee is examining whether contracting failures played a role. Brown said that as much as $10 million was spent for a system that still doesn't work.

Brown held aloft an iPad and shook his head. "We've got cell phones. We've got this and that and you guys are still using three-by-five cards," he said.

During questioning by senators, Kathryn Condon, recently put in charge of Army cemeteries, said that more "discrepancies" have been found since the inspector general's report. Just three of the cemetery's 70 burial sections were surveyed before that report.

"I'm confident that there are probably other map errors," Condon said, referring to where people are buried.

Veterans groups responded angrily to the ongoing disclosures.

Clarence Hill, national commander of the American Legion, referred to a "caustic atmosphere" in the chain of command.

"The idea that cemetery leaders were putting their personal differences in front of their solemn duties is beyond the pale," he said.

Rick Jones, legislative director for the National Association for Uniformed Services, said, "It is hard on families and friends to read reports about unmarked gravesites, improper handling of cremated remains and problems in day-to-day management and operation of this national shrine."