(CNN) The father of one of the two American teenagers accused over the murder of an Italian police officer is returning to the US, but his fight is not over.

Ethan Elder is flying back to the US Saturday after visiting his son Finnegan Lee Elder , 19, in an Italian prison, according to family friend and US criminal defense attorney Craig Peters, who made the trip with him.

"Finnegan's Italian defense attorneys will remain on the case. Our quest for the truth of the events of that night to be made public is moving full steam ahead," Peters told CNN.

Elder and Gabriel Natale Hjorth, 18, are both from San Francisco, but were vacationing together in Rome when police say they took part in last week's assault on Carabinieri officer Mario Cerciello Rega. The officer was stabbed eight times as he tried to recover a stolen backpack from the two, according to police.

Police allege that both confessed to taking part in the assault, with Elder confessing to killing Rega. The two have yet to be indicted on the charges.

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