WAUKESHA, Wis. (CBS 58) -- Federal authorities are searching for a terrorist who was born in Waukesha. A reward of up to $5 million is being offered for information that leads to the arrest and conviction of Jehad Serwan Mostafa. 

"It is under these strenuous circumstances that we remember the role played by our beloved chef, chef Osama bin Laden. May Allah have mercy upon him," Jehad Serwan Mostafa said in a video. 

Investigators called the 37-year-old the highest ranking United States citizen fighting with the Somalian-based terrorist group Al-Shabaab. 

With recent calls by the group encouraging its followers to attack U.S. citizens, the FBI says hunting Mostafa down has become even more urgent. 

"For over a decade, Mostafa has played a critical role in Al Shabaab operations. This includes media operations, training of soldiers, participating on attacks on Somali government forces and African Union troops and holding various leadership positions," said FBI Special Agent Scott Brunner. 

It's unclear what prompted the man to turn to terrorism. While he was born in Waukesha, Mostafa grew up in and graduated college in San Diego in 2004. The FBI says his involvement with the terrorist group started just two years later.