Thieves broke into a builder's house in Malleswaram on Tuesday night and decamped with gold and diamond ornaments worth Rs 20 lakh. According to Malleswaram police, Kumar, a builder, and his wife Anitha Kumari, were away at their relative's place in V V Puram to attend a birthday function. When they returned home around 9.30 pm, the house was in a mess. They found the back door broken and …