WHITE PLAINS, N.Y. -- Investigators called it “Narcy’s secret phone.”

That secret phone, prosecutors say, was used by Narcy Novack to help plan and execute the murders of her husband, Ben Novack, Jr., and his mother, Bernice Novack in 2009.

In closing arguments during her murder trial Tuesday, prosecutors detailed how that phone, and others, were traced to cell phone towers that left a trail of signals from Miami and Fort Lauderdale to Rye Brook, N.Y., an upscale little hamlet nestled just north of Manhattan in Westchester County.

It was in a hotel there, on July 12, 2009, that Ben Novack’s corpse was found next to his blood-soaked bed. He was hogtied, gagged and his eyes were slit.

Cell phones, which operate on signals from towers, were also used by her brother, Cristobal Veliz, who prosecutors say was using various phones in the months, weeks and days before the murders to communicate with the people they hired to commit the murders.

At 6:39 a.m. the morning Ben Novack Jr. was killed, a cell phone tower near the Hilton Rye Town hotel received a ping from the secret phone, showing a call to another phone, which was a few miles away in Port Chester.

The call, according to prosecutors, was made to her brother, whose cell phone was traced to Port Chester, where he and the killers were “waiting for the signal.” The call lasted one minute and 41 seconds. Veliz turned to the killers and told them it was time.

At Veliz’s direction, the two men, Alejandro Garcia and Joel Gonzalez, headed to the hotel in another car, driven by Veliz’s son-in-law, Denis Ramirez. At about the same time, at 6:54 a.m. phone records show that Ben Novack received a call from a hotel manager, who had been helping to mange the overbooked Amway convention Novack was holding at the hotel.

Minutes later, as her husband lay sleeping, prosecutors say Narcy Novack opened their hotel room door and let the two killers in. Armed with hand weights, they pounded at him for 17 minutes, then cleaned themselves up and left him for dead.

The only thing they left behind was a piece of Garcia’s sunglasses, a morsel of evidence that would later prove fruitful for detectives.

Narcy Novack, who watched as her husband screamed in terror, handed them a pillow to silence him, then walked from the fourth-floor suite down to the convention breakfast on the first floor, where she was seen by her daughter, May Abad, and other convention planners, prosecutors say.

At 7:45 a.m. she returned to her room, and her husband’s body. Her key card was the only one used between 12:07 a.m. and 7:45 that morning.

Veliz, who last week testified in his own defense, claims he was nowhere near Rye Brook when Novack was slain. But prosecutors say his cell phone records, bank records, credit card receipts, an ATM video and the testimony of the killers tell a different story. The killers testified earlier that Veliz had been talking to his sister, who wanted her husband and mother-in-law assaulted so brutally that they would be rendered helpless and she could take over her husband’s company — and his wealth.

Novack Jr. was the son of Ben Novack Sr., builder of the Fontainebleau hotel in Miami Beach. After his father lost the hotel to bankruptcy, Novack Jr. began his own successful business, which grossed millions of dollars a year — much of it in cash.