The former executive director of the Russian anti-doping agency planned to write a book on drug use in sports shortly before his sudden death, a former colleague and Britain's Sunday Times newspaper reported Sunday.

Sunday Times sportswriter David Walsh, renowned for his reporting of cycling champion Lance Armstrong's doping, reported that Kamaev wrote to him in November offering to reveal information on doping covering the last three decades since Kamaev began work for a "secret lab" in the Soviet Union.

Kamaev died Feb. 14, aged 52, of what the Russian anti-doping agency called a "massive heart attack."