Los Angeles, California (CNN) -- The judge overseeing the Mel Gibson child custody case ordered a probe into the leak of sealed court documents published on celebrity news website TMZ, a lawyer in the case said.
The confidential documents "were stolen probably from the court" and the leaker "got paid a good deal of money," said Martin Garbus, an attorney for Gibson's ex-girlfriend, Oksana Grigorieva.
Grigorieva and Garbus discussed the leaks in an interview scheduled to air Wednesday night on CNN's "Larry King Live."
"It's medical documents, declarations, court opinions, transcripts, everything it seems," Garbus told King.
TMZ has published sworn statements from Gibson, Grigorieva and another witness in the court fight over custody of 1-year-old Lucia.
"They say over 2,000 pages of documents were leaked and the district attorney's office has started an investigation," Garbus said.
A spokewoman for the Los Angeles district attorney said Tuesday that she was not aware of an investigation.
TMZ's spokeswoman declined to comment on the report of the investigation or the source of the documents.
Lawyers involved in the case had copies, but Garbus suggested the leaked papers likely "came out of the courthouse."
"Whoever took the files from the courthouse -- it's 2,000 pages -- certainly got paid a good deal of money," Garbus said.
The judge ordered the probe on Friday, Garbus said.
A lawyer for Gibson declined to comment, but a publicist for Grigorieva said the leaks did not come from her side.
"It could be quite terrible because this case could turn into a gossip story, and swayed from what's important here," Grigorieva said. "It's domestic violence and Lucia at stake."
She has accused Gibson of domestic violence during their breakup earlier this year, while he accused her of extorting him with tapes she secretly made of their arguments.
The Los Angeles County Sheriff's Department is investigating both accusations.
In another development, Grigorieva's family lawyer, Alan Shifman, stepped aside and has been replaced by Los Angeles attorney Ronald Litz, her publicist confirmed.
Gibson and Grigorieva are both scheduled to return to court on Monday.