North Korea may have executed the official in charge of its nuclear test site facilities, in the second reported execution of a high-ranking party apparatchik in the space of a week.

Park In-young was the head of North Korea’s Bureau 131, a division of the ruling party’s Central Committee tasked with the supervision of military facilities such as the Punggye-ri underground nuclear test facility and the Sohae Satellite Launching Station.

Citing a defector, Japan’s Asahi Shimbun reported that he may have been punished over delays to the sixth and most powerful nuclear test on September 3. It was reportedly originally planned for the spring but was postponed due to delays in the tunnel construction.

“It seems he took the blame as the prolonged mining of the nuclear facility pushed back the test date to September when it was initially set for spring,” said the defector.

But the paper also speculated that his fate may have been sealed by the collapse of a tunnel in October, which allegedly killed around 200 people, but has been officially denied by Pyongyang.