Section 23B. Whoever unlawfully has sexual intercourse or unnatural sexual intercourse, and abuses a child under 16 years of age and has been previously convicted of or adjudicated delinquent or as a youthful offender for: indecent assault and battery on a child under 14 under section 13B; aggravated indecent assault and battery on a child under 14 under section 13B1/2; indecent assault and battery on a person 14 or older under section 13H; assault of a child with intent to commit rape under section 24B; rape of a child with force under section 22A; aggravated rape of a child with force under section 22B; rape and abuse of a child under section 23; aggravated rape and abuse of a child under section 23A; rape under section 22; or a like violation of the laws of another state, the United States or a military, territorial or Indian tribal authority, shall be punished by imprisonment in the state prison for life or for any term of years, but not less than 15 years. The sentence imposed on such person shall not be reduced to less than 15 years, or suspended, nor shall any person convicted under this section be eligible for probation, parole, work release, or furlough or receive any deduction from his sentence for good conduct until he shall have served 15 years of such sentence. Prosecutions commenced under this section shall neither be continued without a finding nor placed on file.

In any prosecution commenced pursuant to this section, introduction into evidence of a prior adjudication or conviction or a prior finding of sufficient facts by either certified attested copies of original court papers, or certified attested copies of the defendant's biographical and informational data from records of the department of probation, any jail or house of correction or the department of correction, shall be prima facie evidence that the defendant before the court has been convicted previously by a court of the commonwealth or any other jurisdiction. Such documentation shall be self-authenticating and admissible, after the commonwealth has established the defendant's guilt on the primary offense, as evidence in any court of the commonwealth to prove the defendant's commission of any prior conviction described therein. The commonwealth shall not be required to introduce any additional corroborating evidence or live witness testimony to establish the validity of such prior conviction.