The ceremony was held to mark the 14th anniversary of DSI establishment. It also came after the DSI was hit by a scandal in which a detainee died in a suspicious environment.
The monk sprinkled holy water onto DSI officials as well as around the premises.
As part of the celebration to mark the 14th anniversary, DSI chief Pol Colonel Paisit Wongmuang led 1,000 DSI officials to take an oath in acting against corruption.
The DSI officials also wore new uniform on Monday to attend the 14th anniversary celebration.