The parents of a severely brain-damaged woman at the center of a right-to-die case say her husband has barred them from visiting her. They are asking a judge to intervene.

The lawsuit is the latest salvo in the long legal battle between Bob and Mary Schindler and Terri Schiavo's (search) husband, Michael -- his wife's legal guardian who is fighting to remove the feeding tube that keeps her alive.

Michael Schiavo (search) blocked all visitors from the Clearwater nursing home where his wife lives after apparent needle marks were found on both her arms March 29. The Schindlers had visited that day.

The Schindlers said they, too, were baffled by the needle marks. Tests found no unauthorized drugs or other substances in Terri Schiavo's blood. Police were investigating, but spokesman Wayne Shelor wouldn't discuss details Tuesday.

In their lawsuit, filed Monday, the Schindlers contend Michael Schiavo, as their daughter's guardian, is consistently late filing the required annual care plans for her. They argue he therefore has no legal right to make decisions for her, or to keep visitors away.

"I'm asking the judge to have a hearing and determine that Michael has been acting without authority and to restore visitation," said Pat Anderson, the Schindlers' attorney.

Deborah Bushnell, an attorney for Michael Schiavo, said he has asked the court for extensions in filing the annual care plans, and blamed delays on "the legal situation." She also defended the bar on visitors until the end of the police investigation.

"We want that all to shake out before instituting visitation," she said.

Terri Schiavo, 40, has been kept alive with a feeding tube after suffering severe brain damage when her heart briefly stopped more than a decade ago.

Her husband contends she never wanted to be kept alive artificially. Her parents doubt she had that wish and believe her condition could improve with therapy.

Terri Schiavo's feeding tube was disconnected for six days in October before Gov. Jeb Bush (search) signed a law requiring it to be reinserted. Michael Schiavo sued Bush, challenging the constitutionality of the hastily passed law that allowed the governor to step in.