The force contains 70 officers.

Mainstream media outlets in the area have avoided reporting on the story, saying they aren't sure if the reporter was writing a story about the mine, or simply trying to blackmail its owner.

An online forum first published reports on Saturday that Lan Chengchang, a reporter with the China Trade News, and two of his colleagues were attacked by a mob at an unlicensed coal mine in Datong's Hunyuan County on January 10, according to a Nanfang City News report yesterday.

The mob beat them with clubs.

Lan died from brain injuries the next day. His colleagues both received broken legs.

The China Trade News confirmed Lan was a reporter for the newspaper for less than two months.

China Trade said it has sent a task force to Shanxi to deal with the incident.

But the Shanxi branch of China Trade was unreachable.

An officer from the Datong city government's office in charge of a campaign against fake media and fake journalists said Lan was not an authentic reporter, however.

The officer said the Shanxi branch of China Trade is a legal news institution, but Lan was a temporary worker at the branch. He didn't have a press card, which you need to report legally in China. The chief of the branch also said he never sent Lan to the coal mine to do stories, the officer added.

The news of his death spread widely on the Internet, but no local media outlets carried a report on the beating.

A reporter from an unidentified newspaper in Shanxi said the incident did happen, but his paper didn't report it because editors were not sure if Lan went to the mine to write a story or to blackmail the mine owner.

Gu Shengmin, an official with Datong's press office, said the truth will be clear when police capture the killers.