A Minnesota man admitted to killing his former girlfriend just days after he was released from jail last summer for assaulting her, according to reports. Matthew Brenneman, 40, pleaded guilty in a Hennepin County Courtroom on Monday to second-degree murder while under a restraining order, KARE-TV reported. He also admitted to two aggravating factors: killing Danicka Bergeson, 33, in the privacy of her own bedroom and treating her with particular cruelty by allowing her body to decompose after death, the outlet reported. In exchange for his plea, prosecutors and Brenneman’s defense team agreed …