The engineer, a man surnamed Yang, jumped off the eighth floor of the Mianyang Municipal Transportation Bureau last week after being asked to take part in the investigation into the collapse of the Panjiang Bridge, local authorities said.
Yang was the chief engineer with the highway division of the transport bureau of Mianyang city in Sichuan Province.
The bridge collapsed in the aftermath of a flood on July 9. Ten people were killed in the collapse.
The engineer was among 60 people and 17 organisations that are being investigated by local procuratorate, state-run Xinhua news agency reported.
Netizens speculated that Yang had killed himself because of his role in the design of the Bridge on the Fujiang River in Jiangyou.