On a recent episode of NCIS, A man, Mike, shot through the bullet holes in two bodies that his daughter-in-law had put into the men as they were standing. She was supposedly a couple hundred yards away, and used a .22 . Mike then shot straight down through the same holes she made, changing the trajectory of the shots, and melding his .45 bullets with the .22 . Is it possible to change the trajectory of the original wounds in this manner, and is it possible to meld a .45 round with a .22 round by shooting in this manner?

A good forensic examination of the body would no doubt find something amiss. You might get away with covering up the original wound once but as in the show you can't be sure of getting rid of all the .22 slugs. Bullets tend to not follow a straight path in a body and as you said, you couldn't know the exact angle anyway. It's bogus because they found the .45 slugs in the boat. All the .22 wounds, that took place outside the boat, would have had to be through and through with the bullets missing. I would be amazed if they only found the one.

Then you have the problem of the blood. Dead men don't bleed the same way live men do. As an experienced investigator, Mike would have known that complicated schemes always go wrong. The two were strangers who could have simply disappeared. The perfect crime is one that no one knows happened. The next best is one that no one knows where or how it happened.