From The New York Times:

They walked parallel paths to trouble, never graduating from high school and racking up arrests. They converted to Islam around the same time and exalted their new faith to family and friends, declaring that they had found truth and certainty. One after the other, both men abandoned their American lives for distant battlefields.

Today, both are dead. While their lives ended five years and over 2,000 miles apart, their intertwined journeys toward militancy offer a sharp example of how the allure of Islamist extremism has evolved, enticing similar pools of troubled, pliable young Americans to conflicts in different parts of the world. The tools of online propaganda and shadowy networks of facilitators that once beckoned Mr. Kastigar and Somali men to the Horn of Africa are now drawing hundreds of Europeans and about a dozen known Americans to fight with ISIS, according to American law enforcement and counterterrorism officials.