Sean Sidi, 19, was last seen in San Francisco on May 21. His family has said he is considered at-risk because he recently suffered a traumatic brain injury.
He does not have his medication with him, and family members are concerned he may be disoriented and confused.
The family hopes the $5,000 reward offered earlier this month is an incentive for people to provide more information about Sidi's whereabouts.
According to his family, hours before he disappeared Sean had visited his former high school at 150 Oak St. in San Francisco.
Sidi's last cellphone call was to his father, Claude Sidi, and made around 1:30 p.m. the day he went missing. It has been traced back to Golden Gate Park.
Because of that information, several searches have since been focused at or near Golden Gate Park.
The family has also set up a donation website to help them raise money for the continued investigation and for more fliers, signs and other ways to keep the search visible.
The family has hired a private investigator to work alongside San Francisco police.
Donations can be made online at donationto.com/searchforseansidi. The family hopes to raise $40,000. As of mid-morning today, $ 27,811 had been donated.
Sidi is described as a slender man of mixed Caucasian and Asian descent, with dark brown hair and eyes and braces on his teeth. He is 5 feet 5 inches tall and weighs 120 pounds. He was last seen wearing a black and gray North Face hooded rain jacket, jeans and black canvas shoes. He recently came out of an arm cast and was wearing a black splint on his left wrist and arm.
Anyone who thinks they may have information on his whereabouts should call San Francisco police Sgt. Ann MacKenzie at (415) 734-3268 or go to www.seansidi.com.