Gabrielson reported on an in-house police force at California's board-and-care institutions for the disabled.

[5] For the East Valley Tribune in 2008, Gabrielson and Paul Giblin investigated the immigration-enforcement operations of the Maricopa County Sheriff's Office.

For this investigation, they won the 2009 Pulitzer Prize for Local Reporting which cited "their adroit use of limited resources to reveal, in print and online, how a popular sheriff's focus on immigration enforcement endangered investigation of violent crime and other aspects of public safety.

"[6] (Giblin had been laid off in Tribune cutbacks at the turn of the year, and Gabrielson announced his departure for the Berkeley fellowship in the summer.

)[2] An associate of a top official at the Maricopa County Sheriff's Department in 2014 unsuccessfully sued Gabrielson for defamation.