HOUSTON — Recorded comments by cult leader David Koresh, which may have been made from FBI electronic bugs inside the Waco cult compound, were played for a federal grand jury before it returned indictments last week.

David Thibodeau of Bangor, Maine, one of a few unindicted survivors of the Branch Davidian cult fire, has twice appeared before the grand jury in Waco, and his mother said Wednesday he was asked to explain tapes of Koresh for the grand jurors.

“I know they had (electronic) monitors in there,” said Balenda Ganem, Thibodeau’s mother. She said that hearing the tapes was “pretty upsetting” to her son.

Thibodeau testified before the grand jury just before the panel issued an indictment expanding charges against 12 cult members accused of conspiracy and other crimes related to the deaths of four federal agents who tried to serve warrants to Koresh on Feb. 28.

The indictment alleged that on April 18 — the day before the fire at the compound — Koresh and his top aide, Steve Schneider, devised a plan to burn their Mount Carmel compound if the FBI moved to end its siege.

Although the indictment provides a clearer outline of the government’s case against the cult members, it also raises questions about whether FBI listening devices alerted authorities to the possibility of a fire. The April 19 blaze killed Koresh and some 80 cult members.

Thibodeau is one of only nine fire survivors. He has remained free as a material witness. Two female survivors are still hospitalized for serious burns. A third woman and five men are either in jail or halfway houses.