A former Russian nuclear physicist turned over 14 ounces of plutonium he found in a dump and then kept in his garage, a news agency said Tuesday. Now he finds himself facing possible criminal charges.

Leonid Grigorov (search) said he had written several letters to authorities urging them to properly secure the eight containers of dangerous material that he said he found discarded near a mining factory in Zmeinogorsk (search) in southern Siberia, the ITAR-Tass news agency said.

When the letters went unanswered, he placed the material in a leaden case in his garage. Each container held 1.75 ounces of plutonium.

"As an expert, I felt obliged to do that to avoid danger," he said, according to ITAR-Tass.

Grigorov turned the plutonium (search) over to police after seeing a police notice inviting people to surrender weapons in exchange for a cash prize. But instead of giving him a prize, police opened a criminal investigation against Grigorov on charges of illegal possession of radioactive materials.

Nikolai Shingaryov, a spokesman for Russia's Federal Atomic Energy Agency (search), said that plutonium-238 is widely used in industries but could not be used to build an atomic bomb.

He would not comment on the ITAR-Tass report but said it appeared unlikely that containers in Grigorov's possession could hold such a large amount of plutonium.

Russia's nuclear chief, Alexander Rumyantsev, has said that authorities have been negligent in disposing of obsolete equipment involving lethal radioactive isotopes during the post-Soviet industrial collapse. Such equipment used for cancer treatment in clinics and in manufacturing industries has been carelessly dumped across Russia.

Since the Sept. 11, 2001, attacks on the United States, concerns have grown that terrorists might be trying to acquire material for a dirty bomb — a device that uses conventional explosives to spread low-level radiation.