...then again, it is Massachusetts isn't it?

I wouldn't give up DNA willingly without benefit. To clear my name would qualify as a benefit. Like EI said, they'd need a warrant.

Also regarding CP's statement about the criminals in CA: Not only have other crimes been solved but some prisoners have been exonerated as well. It can cut both ways.

Is there proof that the person she had sex with is the killer? She could have had sex, left, and then been killed by someone entirely different. As Hog suggested maybe a jealous lover.