LOS ANGELES — Yet another unfinished work by Orson Welles, that master of the incomplete, is about to surface.

Archivists at the University of Michigan said this week that they have discovered extensive fragments of, and notes for, a Welles autobiography in a trove of papers newly purchased from Oja Kodar. Ms. Kodar, a Croatian actress, was Welles’s companion in the years before he died in 1985.

With the working title “Confessions of a One-Man Band,” an unfinished memoir appears to have been in the works since the 1970s, and matches up with additional fragments already in the university’s extensive Welles archive, officials said.

“It’s scattered, we’re still sorting through” about eight boxes of new material, said Philip Hallman, curator of the university’s Screen Arts Mavericks and Makers collection. The papers arrived last week from Croatia, where they had been kept by Ms. Kodar, Mr. Hallman said.