Precedent was set in Terry v. Ohio when the courts ruled that it is reasonable for an officer to perform a limited search and, if necessary, seizure of weapons on a person that the officer reasonably believes could be armed. In this case, an officer noticed an individual (Terry) repeatedly walking up and down the street in front of a particular business while talking to another man and was suspicious that they were "casing" the place for a later robbery. Upon questioning them, he decided that there was ample suspicion to warrant a search of the men, and found a firearm. When the case later went to the Supreme Court for a trial of fourth amendment violation, there was some dissent on the decision. It was ultimately determined that the facts of the case warranted the search and/or seizure (possible violent crime, armed robbery). Simply stated, a policeman on a typical patrol would be unduly burdened without the allowance of search and seizure when circumstances were suspicious.
A Massachusetts case that relied on this precedent set by Terry v Ohio was Harkess v. Commonwealth of Massachusetts. In this case, Officers Bailey and Green were on patrol when they observed two men behaving suspiciously in the Mission Hill housing development, a high-crime area, and gave pursuit. Upon capture, they seized a firearm and some cocaine that had been tossed away. The defendant attempted to use his fourth amendment rights against the police to get out of both the cocaine and an unlawful firearms charge, but due to the Terry v Ohio ruling, this was not possible, and reasonable suspicion was confirmed.
I am linking you to the Massachusetts case information, as well as the Minnesota case referenced above, in the event that I am mis-reading your notation and you did not, in fact, need a Massachusetts case. It seemed a bit of an obscure case, but it did look as though that's what you needed.
Mass case: http://masscases.com/cases/app/35/35massappct626.html
Minn case: http://www.casebriefs.com/blog/law/criminal-procedure/criminal-procedure-keyed-to-weinreb/the-fourth-amendment-arrest-and-search-and-seizure/minnesota-v-dickerson/
I double-spaced this in Word, but the paste function does not permit the formatting to hold--sorry about that! If you copy and paste into your own Word, just highlight and double-space and it should work fine. It's around a page. I hope this was helpful to you. If I can help you in the future, please just request MrsLori.