Supervisor Paul Biane called on his colleagues Tuesday to take polygraph tests and volunteered himself and his staff members to submit to questioning.

District attorney's spokeswoman Susan Mickey said the lawyer heading the investigation has not determined whether polygraph tests would be helpful.

"We are going to do a thorough investigation and not be influenced by anyone from the outside," Mickey said. "This will be conducted just like any other investigation."

Postmus and Supervisors Josie Gonzales and Gary Ovitt all said they would make themselves and their staffs available for lie-detector tests.

Supervisor Dennis Hansberger, whom Biane has accused of leaking the document, said he would take the test if other supervisors did and if the investigation was expanded to look into whether settlement talks occurred outside closed session, in violation of state law.

Mickey said polygraph tests are not admissible in court and the DA's office cannot compel anyone to take one.

And while the supervisors volunteered their employees to take polygraph tests, a lawyer who specializes in labor law said it would be up to the individuals to decide whether they wanted to take the test.

The California labor code specifically states that private employers cannot require employees or job applicants to take lie-detector tests, said Jim Stoneman, a Claremont lawyer. A 1986 California Supreme Court case extended those rights to public employees, he said.

That protection also would apply to at-will political appointees, such as a county supervisor's staff, Stoneman said.

"They cannot be terminated for refusing to give up a lawful right that is theirs, such as a right to privacy," he said.