More than 500 grams of fentanyl were seized during the arrest of a Massachusetts man.
Thirty-six-year-old Rosario Lara of Lawrence has been charged with trafficking a class A narcotic over 200 grams.
Federal, state and local investigators developed information that Lara was trafficking fentanyl, according to state police.
On Thursday, undercover agents arranged to buy the drug from Lara in the Tower Hill area of Lawrence and watched the deal be completed, state police said. Officials then approached Lara, who allegedly attempted to flee the scene.
Police quickly caught the suspect and arrested him. About 532 grams of fentanyl was secured as evidence, state police said.
It's unclear when Lara will be arraigned or if he has an attorney.