A Murder Conviction Torn Apart by a Bullet

Once again, Kopera's notes told a different story.

"Residue in barrel: Yes. Bore condition: Dirty," his notes stated, suggesting that the gun had not been cleaned.

Gun barrels are made with grooves to help bullets travel in a straight path. The barrels leave on bullets impressions known as "lands" and "grooves," which experts measure to match bullets to the guns that fired them.

Kopera testified that he could not conclusively match the markings on the bullet fragment taken from Nueslein's head to Kulbicki's off-duty Smith & Wesson revolver. But that still left open the possibility that the fragment could have come from Kulbicki's gun.

Yet when Drouet finally received Kopera's lab notes, she found that the bullet grooves on the fragment were significantly smaller than those on a bullet fired from Kulbicki's gun.

The fragment's land width was 0.072 inches and its groove width was 0.083 inches, while bullets fired from Kulbicki's gun had a land width of 0.100 inches and a groove width of 0.113 inches, the notes said.

The nearly 30 percent differences in sizes "show conclusively that the Smith & Wesson revolver found in Kulbicki's bedroom did not fire" the bullet that killed Nueslein, Drouet has told the court.

After Kopera committed suicide, prosecutors turned to a new firearms expert to examine the evidence. But his report only raised new questions about whether the markings could have come from Kulbicki's gun.

The groove markings that are impressed on fired bullets twist either to the right or the left. Kopera's 1993 exam made no mention of any twist markings on the bullet fragments, Drouet said. Likewise, the new examiner's report mentioned no twists, she said.

Drouet said that when she questioned the new firearms expert on the stand, however, he acknowledged that he had detected a "slight left twist" marking the fragment. Kulbicki's off-duty weapon makes right-twist markings, Kopera's notes say.

"Every critical part of Kopera's testimony was false, misleading, based on improper assumptions or ignored exculpatory information," Drouet told the judge in her motion seeking a new trial.

The prosecution countered that the twist and size of the bullet fragment markings could have been altered by torque when the fragments broke apart, court records show.