there, kurt moline test fired moeller's rifle into a 600-gallon water tank. >> and i shoot in one end bullets hit the water and they slow down and they drop to the bottom, and then i vacuum those up with a hose. >> he took the test-fired bullet and compared it to slugs recovered from ken maclennan's body. >> the lands and grooves did not match up. a closer examination showed why. a borescope, a fiberoptic mag fireagnifier, revealed a series of abnormal scratches on the inside of the gun barrel. >> the scratches appeared to be fresh. they had scratched through the blueing, which would have been applied at the factory. >> someone had scratched the inside of the barrel for the purpose of preventing a ballistic examination. so, the next step was to compare the spent shell casings from the scene to the casings from the test firing, looking at unique marks made by the firing pin as it struck the bullet. they were identical. also inside the barrel was a small drop of blood. dna testing proved the blood was ken maclennan's. >> it made sense based on the soot on the hand that mr. maclennan had

march, a 2-year-old boy cut himself on razor blades that were glued to playground equipment in east moline. razor blades were also found taped to playground equipment near philadelphia in april. congressman eric cantor is resigning his post as house majority leader, after his surprising loss in virginia's primary election. now, house republicans are looking for his replacement. andrew spencer has more. >> the house majority leader urged conservatives to stay united and its divisions between tea party and so-called establishment republicans. >> truly what divides republicans pales in comparison to what divides us as conservatives from the left. and for the democratic party. >> after a political newcomer beat him in the republican primary, he decided not to wait until the end of his term before resigning his post. >> i think he felt it was better for the party to finish up the business on the table right now and then as we go into the campaigns to have a new majority leader. >> he will resign effective july 31st. next thursday house republicans will hold an election by secret ballot to deter

. >> as it turns out it's a plain clothed detective from nearby east moline, illinois. would have it, the detective, jim weekly, is on his way to meet his wife for lunch when he sees the incident unfold. >> i'm slowing up making sure the officer goes wrong. and that's when i see the glistening of the taser wires in the sunlight. >> detective weekly races around the front of the cruiser and is shocked by what he sees. >> get the [ bleep ] off him! the first thing i see is every officer's worst nightmare. i see the officer on his back. i see the suspect punching him very fast and violently to the face. >> without hesitation, he joins in the melee. >> my job at that point was to get the suspect to start fighting me, to get him off the officer. >> meanwhile, officer anderson is fighting for his life. >> i was basically only able to see shadows. i decided i was going to have to shoot him before i went unconscious, and that's when i shot mr. mallory. >> i don't so much hear the first shot, i felt the first shot. i felt the concussion of it going through my chest. >> weekly mi