Trial begins for U.S. teens accused of killing Italian cop

It was a gruesome killing that shocked Italy and on Wednesday (February 26), the first hearing of the trial of two U.S. students jailed over the murder of a police officer in Rome last year got underway.

Finnegan Lee Elder and Gabriel Christian Natale-Hjorth, both from San Francisco, were arrested in July on suspicion of murdering police officer Mario Cerciello Rega after a dispute following a failed drug deal.

Police say the 35-year-old officer -- who was unarmed and in plain clothes -- was attacked by Elder as he was trying to arrest him and Natale-Hjorth, on suspicion of stealing a backpack from a drug dealer who they believed had cheated them.

Another police officer was allegedly injured in the incident by Natale-Hjorth.

Police say Cerciello Rega was stabbed 11 times with an 7-inch combat knife that Elder brought to Italy from the U.S..

The Americans have said they did not know the man stabbed was a policeman.

However, the city's police chief said at the time that both officers had clearly identified themselves as police to the pair before the attack.

The pair have been kept in a Roman prison and will face charges of murder and attempted extortion.