Vela says formal charges are being sought after funds were missing from one bank account, used mainly in preparation for the March 2 primary, and another account is overdrawn.
Vela says financial problems linked to a worker arose more than a year ago, but she only learned about it this week.
Vela on Wednesday described it as a "terrible day for Democrats."
Vela a day earlier announced she was resigning as leader of the Bexar County Democratic Party so she could run for Bexar County clerk.
