On 1 March 2006 Brendan Dassey confessed to lead investigators Tom Fassbender and Mark Wiegert that Teresa had been shot in Steven Avery’s garage with Steven’s .22 caliber rifle. That same day personnel of Calumet County and the DCI returned to the garage for a 2-day search.
On 14 March 2006 the bullet was sent to the Wisconsin State Crime Lab by Calumet County Deputy Jeremy Hawkins where it was to be examined by DNA Technical Unit Leader Sherry Culhane for the presence of DNA and by ballistics expert William Newhouse.
Culhane's test results
The bullet arrived at the laboratory on Thursday 16 March, and Culhane took custody of it 12 days later, on Tuesday 28 March and began working on the bullet one day later.
Culhane examined the bullet for the presence of DNA. She is a little vague about whether she actually found DNA on the bullet or not, simply saying she did not develop a DNA profile from what was found on the bullet, if anything at all.
Newhouse's test results
In 2005 Newhouse had already received the Marlin Glenfield .22 caliber rifle - the rifle found in Avery's bedroom. Newhouse also received a pack of .22 bullets found in a record cabinet in Steven Avery's bedroom and fired these with the .22 caliber rifle and would examine the lands and grooves left on the bullets he fired with the rifle.
Newhouse also examined the lands and grooves on bullet FK and compared these to the lands and grooves left on the .22 caliber bullets he fired with Steven Avery's .22 caliber rifle.
Based on the lands and grooves Newhouse concluded that bullet FK was fired with a .22 caliber rifle or a rifle with similar characteristics. It could have been fired with Steven Avery's rifle, along with thousands of other rifles.
Bullet FK was mentioned several times at trial, usually together with that other bullet found in the garage, bullet FL, which had Halbach's DNA on it.