The Marlin Glenfield model 60 semi-automatic .22 caliber rifle that Steven had hanging above his bed is the alleged murder weapon. A .22 caliber bullet with the victim's DNA on it was determined to have been fired by this rifle.
Steven claimed he never used this rifle, however two people have said they have seen him use it. In his bedroom a pack of CCI lead bullets were found which can be used for this rifle.
The rifle was bought in the mid 1970's by Roland Johnson, the owner of the red trailer that Jodi and Steven were staying in. Johnson bought it at Fleet Farm and it was one of the cheapest rifles available. It has a scratch somewhere on the rifle. Johnson kept the rifle on a gun rack along with a .50 caliber muzzleloader. When Johnson left his trailer he left pretty much everything there the way it was, including the rifles. The rifle fell in Avery's possession in June 2004, when he moved in with Jodi in the red trailer.
On Sunday 6 November 2005, one day after the discovery of the Toyota RAV4, CASO deputy Daniël Kucharski was assigned by Lieutenant Bowe to search Steven Avery’s trailer to specifically collect any weapons, a vacuum cleaner and bedding from the spare bedroom in the trailer. Throughout the day Kucharski was assisted by three manpower resources from Manitowoc County Sheriff’s Department: James Lenk, Dave Remiker and Andrew Colborn. The men entered the trailer a 12:25 hour and Kucharski collected two guns that were in a gun rack in Steven Avery’s bedroom in the back of the trailer. One was a Marlin Glenfield model 60 semi-automatic .22 caliber rifle. The other was a .50 caliber muzzleloader.
DNA Technical Unit Leader Sherry Culhane examined the rifle for DNA. She found no DNA on the barrel or near the trigger area. Ballistics expert William L. Newhouse examined and performed tests on the rifle from Steven Avery’s bedroom, the bullet pack found in a record cabinet, the shell casings from the garage and the two bullets, also found in the garage.
On 11 May 2006 co-lead investigator Mark Wiegert received a report from the Crime Lab concerning tests done. The tests showed that Bullet FK was fired from a rifle in the Marlin Glenfield series, or a rifle similar to that series. Bullet FL, which was the bullet with Halbach’s DNA, was fired from the Marlin Glenfield found in Steven Avery’s bedroom. According to Newhouse it could not have been fired from any other rifle.
At trial and appeals
2007 Steven Avery trial
The prosecution used the rifle to link Steven Avery to the murder of Teresa Halbach. Firearms expert William Newhouse testified that the rifle was a perfect match with Item FL, the bullet with Halbach’s DNA on it that was recovered from Avery’s garage and testified Item FL could only have been fire from Steven’s rifle and none other.
2007 Brendan Dassey trial
At Brendan’s trial Newhouse provided essentially the same testimony; Item FL, the bullet with Halbach’s DNA, was fired from Steven’s rifle and could not have been fired from any other rifle. The eleven shell casings that were recovered from Avery’s garage were also fired from Steven’s rifle.
2016 - 2021 Kathleen Zellner appeals
Contrary to the State, Zellner believes Halbach was bludgeoned behind the back of her vehicle. Her evidence for this are numerous drops of blood on the cargo door. Zellner has not specifically mentioned the rifle in her tweets or any of her filings. She did present a theory about bullet FL, the bullet that was forensically matched to Avery's rifle, which she believed was a random bullet stuck in Avery's garage wall that someone took and applied Halbach's chapstick to in order to get her DNA on it.