SAN DIEGO -- A grand jury has indicted Chula Vista Councilman Steve Castaneda, who has accused District Attorney Bonnie Dumanis of investigating him to get him to resign, court documents show.

The exact charges against Castaneda have not been unsealed. He is scheduled to be arraigned Thursday in San Diego Superior Court, according to the court's electronic calendar.

A spokesman for the District Attorney's Office declined to comment on the matter, and neither Castaneda's attorney, Marc Carlos, nor prosecutor Patrick O'Toole, who heads the Public Integrity Unit at the District Attorney's Office, returned calls seeking comment.

Castaneda, a Chula Vista councilman since 2004, claimed earlier this year that Dumanis was conducting a "political witch hunt" against him in an effort to get him to resign.

The 47-year-old councilman, who is up for re-election next year, alleged that Dumanis was conspiring with Chula Vista Mayor Cheryl Cox, his opponent in last year's election.

Castaneda said in May that O'Toole's investigation focused on an apartment he rented for his wife in Sunbow Villas, property that he purchased in 2005 with a Chula Vista resident, and his role as a board member of the Chula Vista Redevelopment Corp.