FBI Director Robert Mueller in Boston

BOSTON (MyFoxBoston.com) – FBI Director Robert Mueller is in Boston amid the ongoing investigation into the deadly Boston Marathon bombings that happened last Monday.

Mueller is visiting the field office in Center Plaza. It's unclear what Mueller specifically hoped to address during his stay.

A heavy police presence surrounded the office and Suffolk Superior courthouse in downtown Boston Thursday afternoon.

The FBI is leading the investigation into the April 15 blasts, which left three people dead and more than 260 hurt.

Authorities have charged Dzhokhar Tsarnaev, 19, with using a weapon of mass destruction after they say he and his 26-year-old brother, Tamerlan Tsarnaev, planted a pair of bombs near the finish line of the Boston Marathon. Tamerlan Tsarnaev was killed in an early morning firefight with police on Friday.

Cox Media Group