Yes, if they executed them in said fashion, they need to be punished according to the UCMJ.
If, as I suspect, they did no such thing -- they were either collateral damage, or the Jihadis are staging this -- then every American worthy of the name needs to come down on Murtha and the MSM like a hellfire missile.
They need to do that anyway -- Murtha and the MSM are egregiously beyond the pale.
Let the investigative chips fall where they may. But if it turns out that Marines committed atrocities, then we should be very careful that we don't allow our antipathy toward Murtha and the MSM to blind us to things that are wrong, just because Murtha and the MSM pointed them out to us.