The Trigger-Housing Fingerprints
http://www.jfk-online.com/prints.html
The fingerprint traces found on the side of the trigger housing of the rifle were first photographed and then covered with cellophane tape by Lieutenant Day to protect them for shipment to the FBI lab in Washington, DC. Lieutenant Day had determined that the fingerprints were too light to do a lift first and then photograph, so he photographed the fingerprints before covering them with the tape. (5) He also scratched his name on the stock of the rifle. When testifying later in Washington to the Warren Commission, Lieutenant Day told Rusty and me that he had some trouble finding his name because it was very faint.(6)
As Lieutenant Day worked on the rifle during the evening, Chief Curry came into the Crime Lab Office. Lieutenant Day told him at the time that he had located a trace of a print on the trigger housing, but he had not yet had a chance to do a comparison check with Oswald's print card. He told Rusty and me that the Chief then went back down to the third floor and told the newsmen that we had a print. He said that he had not told Chief Curry that it was Oswald's print at that time.
(...)
Lieutenant Day did not try to lift the fingerprints that he found on the trigger housing of the rifle on November 22nd, 1963. He photographed them only, and later did try to do a fingerprint comparison from a print card of Oswald to determine if he had held the rifle. Day stated to the Warren Commission that he could not exclude all possibility as to whose prints they were, but he did say that he thought that they were the right middle and right ring finger of Oswald.(7)
Tom Alyea has recorded that he watched as Lt Day applied cellophane tape to the print and lifted it from the rifle....
Mr. DAY. After ejecting the live round, then I gave my attention to the rifle. I put fingerprint powder on the side of the rifle over the magazine housing. I noticed it was rather rough. I also noticed there were traces of two prints visible. I told Captain Fritz it was too rough to do there, it should go to the office where I would have better facilities for trying to work with the fingerprints.
Mr. McCLOY. But you could note with your naked eye or with a magnifying glass the remnants of fingerprints on the stock?
Mr. DAY. Yes, sir; I could see traces of ridges, fingerprint ridges, on the side of the housing.
Day said that He placed cellophane tape over the prints to protect them until he could examine them under better conditions in the police lab.