By George P. Hassett

Somerville Police drug unit detectives seized 196 grams of heroin and more than a pound of cocaine in three drug busts over two days last week in East Somerville.

Two of the busts were the result of a cooperating witness who identified Angel Enrique Moreno, 22, and Carlos Euelio Chavez, 38, both of Revere, as main suppliers of heroin and cocaine in the area, police said. Moreno and Chavez were arrested separately, seven hours apart on Friday.

The investigations into Moreno and Chavez began when a search warrant was executed at an undisclosed home on Flint Street and, according to police, heroin and cocaine was found and seized. No arrest was made related to that warrant, said Somerville Police Capt. Paul Upton. He would not say if or how the cooperating witness and the Flint Street warrant were related.

“Joe average citizen doesn’t have the information we need,” Upton said of the use of confidential witnesses. “The drug unit always goes out of their way to protect their sources, as well they should.”

At 11:00 a.m. on Friday, police said Moreno arrived at Flint Street and, as he was stopped by drug unit detectives at the door, allegedly said, “What you are looking for is in my jacket pocket.” In Moreno’s jacket pocket, police allegedly found three clear plastic bags containing 180 grams of heroin.

During a search of his car, police said they found 16 more grams of heroin. The total take, 196 grams, is equal to 10,000 individual bags of heroin and has a street value of approximately $50,000, police said.

Moreno, was arrested and charged with trafficking in heroin and committing a drug violation near a school.

A few hours later cops arrested Chavez after the cooperating witness allegedly arranged for him to deliver 42 grams of cocaine to Flint Street.

Chavez, who police said always wears a red shirt, was stopped by police as he entered the Flint Street home. When police searched his pockets and socks they allegedly found 46 grams of cocaine and three cell phones. He was arrested and charged with cocaine trafficking and committing a drug violation near a school zone.

The next day, Saturday, using information from a confidential source unrelated to Friday’s witness, police targeted Pedro Tapias Lopez, of East Boston, who they described as a Colombian man allegedly distributing large quantities of cocaine.

Investigators learned Lopez was scheduled to make a cocaine delivery to the Dunkin Donuts at Broadway and McGrath Highway. Five minutes before he was scheduled to arrive Lopez was circling the area in his car, police said.

“This circling technique employed by Lopez, is a counter-surveillance safe guard practice utilized by drug traffickers prior to conducting drug transactions,” wrote Detective James Hyde in his incident report.

Police said Lopez arrived at the Dunkin Donuts parking lot with his girlfriend, Claudia Arrendondo, 44, of Quincy. Walking across the parking lot, police said he appeared to be studying the area.

As police approached and confronted Lopez, they said he reached aggressively for his waistline. Hyde and Detective Dominic Pefine neutralized Lopez and allegedly found a knife attached to the waist of his pants.

Police said investigators looking into Lopez’ car could see in plain view an aluminum foil package under the passenger seat. Pefine entered the car, unwrapped the package and found 520 grams, more than a pound, of cocaine, police said.

Lopez and Arrendondo were arrested and charged with trafficking in cocaine, conspiracy to violate a drug law and drug violation near a park. After the arrest, Arrendondo allegedly told police she was not Lopez’ girlfriend.