There seems to be a breakthrough in the case, according to this BBS story. I hope the police can nab this man quickly and the others too:
Police identify man suspected of planting bomb in Dagapela
February 5: The Dagapela police have identified Ganesham Gurung from Baragumti village of Tsendeygang Gewog as the man suspected of planting the bomb in Dagapela on January 20. At the moment, police are searching for him.
Our Tsirang correspondent Sonam Ugyen says photos of the suspect have been distributed at checkpoints in Tsirang and Dagana to help apprehend him.
On January 20, four bombs exploded in various parts of the country. The first explosion took place in Samtse. It was followed by explosions in Thimphu, Gedu, and Dagapela. In Dagapela, the bomb was planted behind the house of a former Gup of Tsendeygang gewog.
Ganesham Gurung the man suspected of planting the bomb disappeared on the day the closely coordinated blasts took place. He is suspected of planting the bomb under the instructions of militants based in Nepal.
Our Tsirang correspondent spoke to several people in Tsirang and Dagana. They said the bomb blasts have only strengthened their resolve to participate in the elections and ensure the success of parliamentary democracy in the kingdom.