DENVER (AP) — Activists asked a U.S. judge Thursday to make documents public from a 27-year-old criminal investigation into a former nuclear weapons plant outside Denver with a history of fires, leaks and spills.

The activists said the documents could show whether the federal government did enough to clean up the site before turning part of it into a wildlife refuge and opening it to the public.

The government built plutonium triggers at the Rocky Flats plant from 1952 to 1989. It was shut down after a two-year grand jury investigation into environmental violations.

After the investigation, Ro...