WASHINGTON  BP spent months this summer trying to contain the gusher of oil on the floor of the Gulf of Mexico. Now the company is trying to contain the legal and financial fallout from the explosion of the Deepwater Horizon, and on Wednesday it released the results of an internal investigation that mostly pointed fingers at other companies.

Conducted by the company’s safety chief, Mark Bly, and a team of about 50 made up mostly of BP employees, the inquiry was initiated almost immediately after the April 20 explosion that killed 11 and spilled almost five million barrels of oil into the ocean.

The 193-page report is part mea culpa, part public relations exercise, but mostly a preview of BP’s legal argument as it prepares to defend itself against possible criminal or civil charges, federal penalties and hundreds of pending lawsuits.

The report deflects attention from BP and onto its contractors, especially Transocean, which owned the rig, and Halliburton, which performed cement jobs on the well. It also focuses less on decisions that BP made in designing and drilling the well than on what rig workers, from Transocean and Halliburton, did in the hours leading up to the blowout.