A bottle of bleach was discovered in Steven Avery’s trailer following Brendan Dassey's confession on 1 March 2006. The bottle was empty.

During his confession Brendan Dassey told investigators that on 31 October 2005 a couple of hours after the victim had arrived at Avery’s Auto Salvage, he and his uncle cleaned a “red fluid” from his uncle's floor, invariably described by Brendan as 'car fluids' or 'blood'. Despite there being many stains on the garage floor already seemingly not attempted to be cleaned, Brendan and his uncle decided to clean this fresh spot. Brendan said the materials they used to clean the red fluid were gasoline, paint thinner and bleach.

During the cleaning some bleach got on Brendan's jeans and they left a permanent stain. Brendan explained that while he was cleaning the red fluid he made sure he didn't come in contact with it. Nothing of the red fluid came on his clothes.