FILE - In this Aug. 30, 2013 file photo, David Koch speaks in Orlando, Fla. Koch, major donor to conservative causes and educational groups, has died on Friday, Aug. 23, 2019. He was 79.

WASHINGTON (AP) — Billionaire conservative donor Charles Koch (kohk) is remembering his brother David Koch for "his giant personality and passion for life" and says he will be "greatly missed, but never forgotten."

Charles Koch and David Koch together were major donors to conservative causes and educational groups. David Koch died Friday at age 79.

Charles Koch says his brother was diagnosed with advanced prostate cancer 27 years ago but liked to say that "brilliant doctors, state-of-the-art medications and his own stubbornness kept the cancer at bay." Charles Koch says his brother "was able to touch so many more lives as a result" in the ensuing years.

He says his brother got married, had three children and remained dedicated to Koch Industries, based in Wichita, Kansas.

The brothers each had an estimated net worth of $50.5 billion, tied in 11th place in 2019 on the Forbes 500 list of the nation's richest men.

Frederick Koch, one of David Koch's older brothers, is listed on Butler County property records as the owner of a large historic mansion in the city of Butler commonly known as Elm Court or the Phillips mansion.