. >> with this information, greg leskowski took a second look down the barrel of cliff merck's gun andence of what the informant was talking about. >> the land impressions at the very muzzle or the crown of the barrel had appeared to have been altered. it wasn't obvious at first because it's an old gun, but there was just something about the crown and the land impressions of that muzzle that were just different from the remainder of the impressions farther down the barrel. >> since only the end of the barrel had been altered, leskowski needed to find some way to examine just the portion of the barrel that was unaltered. no one in the forensic establishment could help him. >> i contacted a number of known experts about what i was planning to do and how to do it. they all wished me good luck. and so, you know, i felt i had to, you know, i was kind of just working on my own at that time. >> but leskowski remembered using a dental casting material called mikrosil in a case where he needed to see tool marks in a piece of metal. so, he decided to try some of that by putting it down the barre