BySiladitya Ray,

Forbes Staff.

Former Vice President Dick Cheney, one of the key figures who oversaw the U.S. government’s response to the 9/11 terror attack and is considered to be the most powerful person to have served in the role, died Monday at the age of 84.

In a statement Tuesday morning, the Cheney family said the former vice president died on Monday night “due to complications of pneumonia and cardiac and vascular disease.”

The statement said Cheney’s wife of 61 years, Lynne, his daughters, Liz and Mary, and other family members were with him as he passed.