Israeli police began searching the nearby neighborhoods in Jerusalem and Arab villages around where Sofer went missing last Friday. Sofer and his hiking companion apparently became separated while navigating down a steep slope, Merhav Tzion Deputy Commander Motti Levy said Thursday.
The Sofer family, who have traveled from New Jersey to Israel to help in the search, is offering 100,000 shekels ($28,093) for information that leads to finding Sofer.
Intelligence officials say there remains no conclusive proof of a terrorist abduction, but said the circumstances make kidnapping likely. While no terror group has taken credit that is not unusual: Hamas only recently admitted to the kidnapping and killing three Israeli teens that set off this summer's violent clashes in Gaza.
The forest where Sofer disappeared is the same forest where a 16-year-old Arab-Israeli teen was found murdered in revenge for the three teens' kidnappings.
Notable deaths of 2014 [PHOTOS]
Father of murdered schoolgirl Sarah Payne dies