porter pleaded guilty to charges of second-degree murder in the 1960 fatal shooting of 22-year-old part-time clothing store clerk, john pigott, at the robert hall clothing store in saugus, massachusetts with a sawed-off shotgun. in 1961, while awaiting trial on those charges, porter was involved in the fatal assault in and shooting of the head jailer, david s. robinson, at middlesex county jail in cambridge, massachusetts and escaped from prison only to be captured while holding up a grocery store in new hampshire. he also pleaded guilty to charges of second-degree murder in that case, and was sentenced to two consecutive terms of life imprisonment.