Undercover Somerville police officers discovered 10 bags of what they believed to be heroin after stopping a car at the intersection of  Mystic Avenue and McGrath Highway on Sept. 6, according to a Somerville police report.

Officers made the traffic stop after they observed the driver make an alleged drug deal with the resident of a Hinckley Street home that was under surveillance, the report says. A Jaques Street home with a history of drug problems was also involved in the incident, according to the report.

According to the report, investigators received information that the first-floor residents of the Hinckley Street home were constantly using crack cocaine and heroin.

They put the home under surveillance, and at around 4 p.m. detectives observed one of the residents leave the home, holding cash in his hands, and get in a Ford Taurus, the report says.

The car looped around the block, and then the resident got out of the car, this time without cash in his hand, according to the report.

Detectives followed the car to a Jaques Street home that already had a reputation for being a center of drug use and distribution, according to the report, which pointed out police had raided the home on March 22. In 2010, the same home—37 Jaques Street—was the site of a three-hour standoff between a gunman and a SWAT team.

When the car left the Jaques Street home, police pulled it over.

The driver, Luis Arroyo-Morales, 34, of Roslindale, had $520 in cash, according to the report. 

Detectives also discovered 10 clear plastic bags filled with what's believed to be heroin hidden in a magnetic hide-a-key box, the report alleges.

Officers arrested Arroyo-Morales and charged him with drug possession to distribute.

Please remember that allegations contained in police reports do not indicate a conviction.