Cambridge police arrested a man Monday wanted in a robbery and shooting after spotting him taking out the garbage at a house on River Street in Mattapan.

The man, Isidoro Diaz, also known as Tito Diaz, allegedly robbed three people as they walked down Spring Street on a Saturday evening last month.

Diaz, who is 19 years old and whose last known address was in Cambridge, is said to have confronted the trio along with five accomplices and demanded their money. After the people surrendered their money, Diaz opened fire with a shotgun, wounding one victim in the shoulder and the other in the buttocks.

Cambridge detectives John Fulkerson and William Phillips staked out the Mattapan house after a month-long investigation. After spotting Diaz bringing out trash barrels from the house, the police confronted him and he fled inside. Boston police were able to surround the house and arrest Diaz without incident.

Diaz was arraigned in the Third District Court yesterday morning on three counts of assault with intent to murder and three counts of armed robbery. The court ordered him held without bail.

House of Blues Arrest

Only one day before arresting Diaz, the Cambridge Police Department brought in a 22-year old man for disorderly conduct at the House of Blues and discovered they had arrested a fugitive wanted by the United States Marshall's Office.

Cambridge police arrested a man who identified himself as Christopher Chilgren of St. Paul, Minnesota on Winthrop Street after he allegedly caused a disturbance at the House of Blues, a jazz bar off Harvard Square.

During a booking search, police recovered a Wisconsin driver's license in the name of Robert M. Shimek in Chilgren's wallet. While Chilgren claimed that he had stolen the license, Identification Sergeant John Drewicz reviewed a file of outstanding federal warrants and fingerprints and concluded that the two men were one and the same.

Chilgren was being held for disorderly conduct, but the Drug Enforcement Administration had a warrant out for Shimek on conspiracy to manufacture and produce marijuana.

The man with two names has been delivered to the United States Marshall's Office where he faces indictment for both sets of charges.