(Milwaukie, OR)  --  A Milwaukie man who pleaded guilty to fatally stabbing his grandmother is scheduled to spend the rest of his life behind bars.  Eighteen-year-old Andrew Johnson was charged with murder in the death of 63-year-old Donna Tennant in December 2012.  Police say Johnson repeatedly stabbed Tennant in her sleep and then took pictures of her body and bragged about it to his friends.  Johnson will be eligible for parole in 25 years.