Supreme Judicial Court (March 24, 2008)

A prosecutor's statements made during closing argument about his retracing the steps of a key witness amounted to unsworn testimony and vouching, both of which are improper argument and, in this case, constituted reversible error.

The defendant was tried before a jury for a gang-related murder. The Commonwealth's key witness testified that he drove the defendant and co-defendant to the area where the shooting took place. During closing argument the prosecutor stated he knew the key witness was being truthful, because after first interviewing the witness, the prosecutor got into his car and retraced the route that the witness had described. The defendant was convicted of first degree murder.

The defendant appealed his conviction and claimed that the prosecutor engaged in multiple acts of misconduct during closing argument, including giving unsworn testimony which corroborated the testimony of the Commonwealth's key witness, and personally vouching for the credibility of the witness:

"After I had been to all of those locations, I knew, and I suggest to you you know, that Shawn Castle was able to say that and tell us that because he was there. They were there on the tenth of June, 1994…. Shawn Castle, I suggest to you, told you the truth. And after seeing all of those things, Shawn Castle was given a deal. And the very next day you heard, the very next day, he was before the … grand jury, and he told them what he had seen."

The SJC agreed with the defendant, ruling that "in cases where a prosecutor improperly has given testimony that went to a critical issue in the case, or improperly has vouched for a key Commonwealth witness . . . . we have required a judge to respond to prosecutorial misconduct with force and specificity. A general instruction, as here, will not suffice to neutralize the prejudice. A new trial is required."