Section 15B. (a) Whoever, by means of a dangerous weapon, commits an assault upon a person sixty years or older, shall be punished by imprisonment in the state prison for not more than five years or by a fine of not more than one thousand dollars or imprisonment in jail for not more than two and one-half years.
Whoever, after having been convicted of the crime of assault upon a person sixty years or older, by means of a dangerous weapon, commits a second or subsequent such crime, shall be punished by imprisonment for not less than two years. Said sentence shall not be reduced until one year of said sentence has been served nor shall the person convicted be eligible for probation, parole, furlough, work release or receive any deduction from his sentence for good conduct until he shall have served one year 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 said offender a temporary release in the custody of an officer of such institution for the following purposes only: to attend the funeral of next of kin or spouse; to visit a critically ill close relative or spouse; or to obtain emergency medical services unavailable at said institution. The provisions of section eighty-seven of chapter two hundred and seventy-six relative to the power of the court to place certain offenders on probation shall not apply to any person seventeen years of age or over charged with a violation of this subsection.
For the purposes of prosecution, a conviction obtained under subsection (a) of section fifteen A or paragraph (a) of section 18 shall count as a prior criminal conviction for the purpose of prosecution and sentencing as a second or subsequent conviction.
(b) Whoever, by means of a dangerous weapon, commits an assault upon another shall be punished by imprisonment in the state prison for not more than five years or by a fine of not more than one thousand dollars or imprisonment in jail for not more than two and one-half years.