Andrew Terraciano will not return as Sean Reagan in the spinoff, and Mika Amonsen will now take his place in 'Boston Blue'

The Blue Bloods spin-off series, Boston Blue, is officially in the works — but without one of its original cast members.Donnie Wahlberg’s character from the crime procedural, Danny Reagan, will be returning along with his son,

Mika Amonsen will play Sean Reagan in the 'Blue Bloods' spinoff, 'Boston Blue,' a role previously played by Andrew Terraciano.