A dozen people have been found accountable for lapses that contributed to the massive mistaken shipment of live anthrax samples from a U.S. Army laboratory in Utah, an investigation report said Friday.

They include Brig. Gen. William E. King, who then as a colonel commanded the Dugway Proving Ground laboratory between 2009 and 2011. The Army investigation report accused him of actions that "perpetuated a complacent atmosphere" among lab workers.

Those oversight and laboratory deficiencies may have been contributing factors, but there is insufficient evidence to establish any single failure as the proximate cause for the inadvertent shipment, the report said.

It also said the inadvertent shipment is "a serious breach of regulations, but did not pose a risk to public health."

In late May, the Pentagon announced that the Dugway lab sent live anthrax samples to laboratories in nine U.S. states, as well as an American military base in South Korea. Further mistaken shipments have since been revealed, bringing the total to 194 in the U.S. and nine in foreign countries.

The bacteria should have been made inactive before being shipped.

Anthrax is a lethal disease caused by Bacillus anthracis, but the term is commonly used to refer to the causative agent itself.

In 2001, anthrax-laced letters were mailed to U.S. news media and Senate offices, killing five people

(Yonhap)