ROME (AP) — A lawyer for one of two American teens jailed in the investigation of an Italian police officer's slaying has petitioned for his client's release. Francesco Petrelli said Friday he didn't know when a tribunal would hear the appeal, filed a day earlier, on behalf of Gabriel Christian Natale-Hjorth, 18. Natale-Hjorth and fellow Californian Finnegan Lee Elder, 19, are being held in a Rome jail while prosecutors probe the slaying of an unarmed officer, Mario Cerciello Rega, who was knifed 11 times on July 26. Prosecutors contend Elder stabbed the officer during a scuffle while Natale-Hjorth allegedly punched and kicked the officer's partner. The plainclothes officers were investigating an alleged extortion attempt by the teens involving a stolen knapsack. Prosecutors say Elder claims self-defense and that both teens say they didn't realize the two men were police officers. Elder's father, Ethan Elder, said in a statement after a jailhouse visit with his son on Friday: "It was good to see Finnegan, who is struggling but holding up." The statement said family members were working with the young man's lawyers to "establish all the facts."