By George P. Hassett

Somerville Police and FBI agents have arrested a suspect who is charged with the Dec. 4 robbery of the Citizens Bank at 212 Elm Street in Davis Square.  Ricardo Colazzo, age 37, was arrested Dec. 8 by Somerville detective John Oliveira and FBI agents.

Shortly after 10 a.m. on December 4,  police allege that Colazzo entered the Citizens Bank and passed a note demanding cash and threatening that he had a gun.  He fled the bank after being given an undisclosed amount of cash.

In the days following the robbery, Detective Oliveira, who is assigned to the FBI Bank Robbery Task Force and other FBI agents were able to identify Colazzo as a potential suspect, police said.  He was allegedly identified by his probation officer from viewing bank surveillance pictures.

Detective Oliveira obtained an arrest warrant for Colazzo and he was arrested in Boston on Wednesday.  He was booked at Somerville Police Headquarters.  A subsequent search at the shelter where  Colazzo had been living led to the recovery of a jacket and gloves that police believe were used in the robbery, police said.