The reward is up to $100,000 for solving the 1999 disappearance of an 11-year-old southeast Kansas boy whose adoptive parents never reported him missing.
An anonymous donor who wanted to see closure for the family of Adam Herrman put up a $50,000 cash reward in December.
Butler County Sheriff Kelly Herzet announced Thursday that an additional $50,000 is now offered.
Herzet told reporters he personally does not believe Adam is still alive.
Adam disappeared from the adoptive family’s Towanda home in 1999 but wasn’t reported missing until 2008, when his older sister contacted authorities. He remains the subject of a missing person investigation.
His adoptive parents, Doug and Valerie Herrman, were convicted in 2011 of continuing to receive state adoption subsidies after Adam disappeared.
Associated Press information from: KWCH-TV