The most "valuable" hostages were three North Americans, Martin and Gracia Burnham, a missionary couple, and Guillermo Sobero, a Peruvian-American tourist who was later beheaded, following a $1 million ransom demand. The hostages and hostage-takers then returned to Abu Sayyaf territories in Mindanao. According to Bowden, the leader of the raid was Abu Sabaya. According to Gracia Burnham, she told her husband "to identify his kidnappers" to authorities "as 'the Osama bin Laden Group,' but Burnham was unfamiliar with that name and stuck with" Abu Sayyaf. After returning to Mindanao, Abu Sayyaf conducted numerous raids, including one that culminated in the Siege of Lamitan and "one at a coconut plantation called Golden Harvest; they took about 15 people captive there and later used bolo knives to hack the heads off two men. The number of hostages waxed and waned as some were ransomed and released, new ones were taken and others were killed." On 7 June 2002, about a year after the raid, Philippine army troops conducted a rescue operation in which Martin Burnham and Filipino nurse Ediborah Yap were killed. The remaining hostage was wounded and the hostage takers escaped. In July 2004, Gracia Burnham testified at a trial of eight Abu Sayyaf members and identified six of the suspects as her captors, including Alhamzer Limbong, Abdul Azan Diamla, Abu Khari Moctar, Bas Ishmael, Alzen Jandul, and Dazid Baize. "The eight suspects sat silently during her three-hour testimony, separated from her by a wooden grill. They face the death sentence if found guilty of kidnapping for ransom. The trial began this year and is not expected to end for several months." Alhamzer Limbong was later killed in a prison uprising. Burnham claimed that Philippine military officials were colluding with her captors, saying that the Armed Forces of the Philippines "didn't pursue us...As time went on, we noticed that they never pursued us". On 10 June 2007, Italian priest Reverend Giancarlo Bossi was kidnapped near Pagadian, capital of Zamboanga del Sur Province in the southern Philippines. Pope Benedict XVI made an appeal to free him. Bossi was released on 19 July 2007 at Karumatan, a Muslim town in Lanao del Norte Province, allegedly after the payment of ransom.