Pen. Code, § 969b

For the purpose of establishing prima facie evidence of the fact that a person being tried for a crime or public offense under the laws of this State has been convicted of an act punishable by imprisonment in a state prison, county jail or city jail of this State, and has served a term therefor in any penal institution, or has been convicted of an act in any other state, which would be punishable as a crime in this State, and has served a term therefor in any state penitentiary, reformatory, county jail or city jail, or has been convicted of an act declared to be a crime by any act or law of the United States, and has served a term therefor in any penal institution, the records or copies of records of any state penitentiary, reformatory, county jail, city jail, or federal penitentiary in which such person has been imprisoned, when such records or copies thereof have been certified by the official custodian of such records, may be introduced as such evidence.