Three members of a sophisticated heroin and methamphetamine ring have been arrested in a major bust that netted over $12 million worth of elaborately hidden drugs, authorities said.

In two of the drug ring's Manhattan stash apartments, authorities found $12 million worth of heroin -- 20 kilograms weighing roughly 44 pounds -- and about $500,000 worth of crystal meth in various hidden compartments, according to the Drug Enforcement Administration. Investigators believe the narcotics were intended for distribution in New York, Pennsylvania, Massachusetts, and other locations.

Pablo Paulino, 36, of Manhattan; Pedro Abreu, 55, of the Bronx; and Janeison Garcia 28, of Orlando, Fla., were arrested Monday night and charged with multiple counts of criminal possession of a controlled substance. More charges could be filed, officials said.

The defendants were arraigned Tuesday night in Manhattan Criminal Court. Abreu and Paulino were held without bail. Bail for Garcia was set at $250,000.

The arrests followed a long-term investigation and several days of continuous surveillance by authorities of 111 Wadsworth Ave., Apt. 21E, in Washington Heights, where investigators and agents saw the three men repeatedly entering and leaving while carrying bags, officials said.

Inside, authorities found a safe with $120,000 cash inside. Continuing their search, they discovered a "trap" or hidden compartment behind the wall of the bathroom, accessible by removing a panel of four tiles. The trap contained about 17 pounds of methamphetamine, along with shoe soles that had been ripped from several pairs of women's footwear. International traffickers commonly use hollowed-out shoes to conceal drugs, officials said.

Also seized from the apartment were 100 grams of heroin from the pocket of a jacket inside a closet, numerous cellphones, and "drug ledgers," officials said.

In a second stash apartment in the same building, authorities found a sophisticated "counter surveillance" system, including two pinhole cameras concealed in the frame of the apartment's front door, officials said. The cameras recorded activity in the public hallway and fed live video to a monitor mounted above the door inside the apartment, as well as to a DVR that recorded the feed.

Authorities said they also found 11 kilograms of heroin -- more than 24 pounds -- in brick form. The drugs were hidden inside a trap in a kitchen cabinet and accessed through a sliding panel on the back wall of the cabinet, which was visible only after the shelves of the cabinet had been removed, officials said.

An additional 5 kilograms, or 11 pounds, of heroin were tucked between a mattress and box spring of a bed in a bedroom, officials said. A TV stand with storage components in the living room contained another kilo of heroin, officials said.

Behind a wall in the bathroom of one apartment, agents discovered a trap that could be accessed by removing the medicine cabinet. Inside, investigators recovered two large bags containing more than two kilograms, or 5 pounds, of heroin, authorities said. Also seized from the apartment were packaging materials and "kilo presses" designed to compress heroin into brick form, officials said.

The operation was carried out by the New York DEA office with assistance from the office of New York City's special narcotics prosecutor, Nassau and Suffolk police, Village of Hempstead police, the Nassau district attorney's office, the Suffolk County sheriff's office, and the Suffolk County district attorney's office. The NYPD's Narcotics Borough Manhattan South also assisted in making the arrests.