In three vehicles linked to Mendez-Lazaro, 33, and Gomez-Veloz, 39, that were outside the apartment, police found about six kilograms of heroin, which they said had a street value of $2 million.
Montgomery County District Attorney Risa Vetri Ferman said authorities do not know the extent of the trafficking operation or where the drugs were sold.
"We just happened upon this in the midst of assisting other jurisdictions outside of Pennsylvania in the location and apprehension of a fugitive," she said Monday. "While they were not on our radar and we have no information to suggest their past activities were in the county, I'm certainly pleased we were able to take this significant amount of drugs out of the market."
The investigation began Sept. 18 when federal authorities and the Bergen County (N.J.) Prosecutor's Office asked Montgomery County to help catch Mendez-Lazaro, who was wanted on three counts of attempted murder of a police officer, eluding, and other offenses.
On Aug. 23, Mendez-Lazaro, who was staying in a Bergen County motel, tried to flee from officers questioning him about documents in his car regarding "some type of U.S. Customs drug-related or money-laundering investigation," according to the arrest affidavit.
He ran away and got into an unmarked police car and drove toward the officers, hitting two. One fell to the ground, and another was dragged by the vehicle.
Mendez-Lazaro escaped to New York. Law enforcement officials eventually learned that Mendez-Lazaro had ties to Montgomery County and might have been staying in the Lower Gwynedd apartments. Thursday, police found Mendez-Lazaro and Gomez-Veloz in the apartment.
The two are being held at the Montgomery County Correctional Facility. Their preliminary hearings are scheduled for Oct. 9 in District Court.
In addition to the Montgomery County District Attorney's Office and the Lower Gwynedd Police Department, also participating in the investigation were the Montgomery Township Police Department, the Bergen County Prosecutor's Office, the U.S. Department of Homeland Security, and the Drug Enforcement Administration.