The Amal militia conducted repeated guerrilla attacks against Israeli soldiers stationed in southern Lebanon.
The safety of the camps was then entrusted to the Amal militia.
The dead neighbor's family was reported to have alerted the Amal militia, the Shiite Muslim force that has taken charge of security for the area.
He said the Amal militia took part in protecting Mr. Do until his departure Tuesday.
He studied literature at a private school and joined the Amal militia in 1978.
Meanwhile, leaders of the Amal militia, who had met with Colonel Higgins just before his abduction, mounted a massive search for him.
The Party of God is currently preoccupied with fighting against the Amal militia, a rival Shiite group.
In Beirut the siege of the Palestinian refugee camps by the Amal militia had just ended and the starving inmates were finally being allowed to leave.
The Amal militia was a major participant in the Lebanese Civil War.
Minutes later, his flight was hijacked, prosecutors say, by a team of Amal militia led by Mr. Yunis.