Subsection (2) of section 178 K of chapter 6 of the General Laws, as amended by section 6 of chapter 303 of the acts of 2006, is hereby further amended by adding the following paragraph:-

(f) No sex offender classified as a level 3 offender shall establish a residence within 1,000 feet of any elementary or high school.  Any sex offender who violates this paragraph shall, for a first conviction, be punished by imprisonment for not more than 30 days in a jail or house of correction; for a second conviction, be punished by imprisonment for not more than 2 ½ years in a jail or house of correction nor more than 5 years in a state prison or by a fine of not more than $1,000, or by both such fine and imprisonment; and for a third and subsequent conviction, be punished by imprisonment in a state prison for not less than 5 years; provided, however, that the sentence imposed for such third or subsequent conviction shall not be reduced to less than 5 years, nor suspended, nor shall any person sentenced herein be eligible for probation, parole, work release or furlough, or receive any deduction from his sentence for good conduct until he shall have served 5 years.  Prosecutions commenced hereunder shall neither be continued without a finding nor placed on file.