The woman allegedly stole a 780-year-old relic of St. Anthony from St. Anthony Catholic Church in Long Beach on June 6.
The relic was recovered three days later.
Maria Solis, 41, was arrested.
Los Angeles County District Attorney's spokeswoman Sandi Gibbons told the Long Beach Press-Telegram Friday that neither St. Anthony's parish in Long Beach nor the Archdiocese of Los Angeles wanted to pursue a case.
District attorney records say Solis has no prior record, lives near the church at a facility for the mentally ill and it was unlikely it could be proven she entered the church with intent to steal.
The Associated Press contributed to this report.