Section 10G. (a) Whoever, having been previously convicted of a violent crime or of a serious drug offense, both as defined herein, violates the provisions of paragraph (a), (c) or (h) of section 10 shall be punished by imprisonment in the state prison for not less than three years nor more than 15 years.

(b) Whoever, having been previously convicted of two violent crimes, or two serious drug offenses or one violent crime and one serious drug offense, arising from separate incidences, violates the provisions of said paragraph (a), (c) or (h) of said section 10 shall be punished by imprisonment in the state prison for not less than ten years nor more than 15 years.

(c) Whoever, having been previously convicted of three violent crimes or three serious drug offenses, or any combination thereof totaling three, arising from separate incidences, violates the provisions of said paragraph (a), (c) or (h) of said section 10 shall be punished by imprisonment in the state prison for not less than 15 years nor more than 20 years.

(d) The sentences imposed upon such persons shall not be reduced to less than the minimum, nor suspended, nor shall persons convicted under this section be eligible for probation, parole, furlough, work release or receive any deduction from such sentence for good conduct until such person shall have served the minimum number of years of such sentence; provided, however, that the commissioner of correction may, on the recommendation of the warden, superintendent or other person in charge of a correctional institution or the administrator of a county correctional institution, grant to such offender a temporary release in the custody of an officer of such institution for the following purposes only: (i) to attend the funeral of a spouse or next of kin; (ii) to visit a critically ill close relative or spouse; or (iii) to obtain emergency medical services unavailable at such institution. Prosecutions commenced under this section shall neither be continued without a finding nor placed on file. The provisions of section 87 of chapter 276 relative to the power of the court to place certain offenders on probation shall not apply to any person 18 years of age or over charged with a violation of this section.

(e) For the purposes of this section, ''violent crime'' shall have the meaning set forth in section 121 of chapter 140. For the purposes of this section, ''serious drug offense'' shall mean an offense under the federal Controlled Substances Act, 21 U.S.C. 801, et seq., the federal Controlled Substances Import and Export Act, 21 U.S.C. 951, et seq. or the federal Maritime Drug Law Enforcement Act, 46 U.S.C. App. 1901, et seq. for which a maximum term of imprisonment for ten years or more is prescribed by law, or an offense under chapter 94C involving the manufacture, distribution or possession with intent to manufacture or distribute a controlled substance, as defined in section 1 of said chapter 94C, for which a maximum term of ten years or more is prescribed by law.