It was the coldest of cold cases for three decades. Now, a 69-year-old Minocqua is pleading not guilty to first-degree murder charges in the 1982 death of his wife. Barbara Mendez was beaten to death, with her body found at the Park City Credit Union office where she worked. Robin Mendez made an Oneida County court appearance Thursday to enter his plea. Most of the evidence in the 36-year-old case is said to be circumstantial. The sheriff’s office says the television crime show “Cold Justice” offered resources and fresh eyes which helped lead to the arrest.