A New York teenager mysteriously disappeared after he took an impromptu road trip to Tennessee. His truck was located years later, but family and law enforcement are still searching for him.

In 2011, Nieko Lisi, then 18, was preparing to apply to the military to become a Navy Seal, like his father. But on Sept. 30 that year, Lisi and a friend, Robbie Knight, got in a stolen 2004 GMC pickup truck and left rural Steuben County.

Concerned family accessed Lisi’s phone records and discovered the teenager had traveled from New York to Michigan and then down to Tennessee, where his phone pinged for the last time on Flintrock Drive in Franklin at 4:05 p.m. on Oct. 1.

Lisi had a connection to the small town around 30 minutes outside Nashville since he had spent the summer of 2009 and part of his junior year of high school living there with an aunt and uncle.

On Oct. 3, two days after that final ping, Monica Button says she received a letter addressed to her son. When she opened the envelope, she found Lisi’s license and an attached note that said the document was found on the ground in Upstate New York.

The following day, family contacted the father of Lisi’s traveling companion, Knight, and learned Knight was with the Michigan State police.

Rachael Davis, Lisi’s aunt, says that when Knight was questioned by law enforcement in Michigan, he had “some sort of psychiatric episode” and he was taken to a hospital for evaluation.

On Oct. 11, Lisi’s family learned some more troubling news: Robbie Knight was dead of an apparent overdose of prescription medication. “I had sympathy for his family,” Davis says, “but as Nieko’s aunt I was more worried about would we ever find out what happened to him.” She adds, “As far as we knew, Robbie was the last link to Nieko.”

According to Lisi’s mother, on Oct. 15, she was able to use her son’s phone records to identify a young man who may have known something. Button says the young man told her Lisi had stayed with him on Oct. 1 in Franklin but then disappeared.

Button noted that while driving from New York to Tennessee, her son and the young man exchanged a total of 36 phone calls. “So what were they talking about on the phone is my question,” she says, noting the mystery “has never been answered.”

Months passed with no new leads in the case. Finally, in March 2012, Button traveled to Tennessee to speak with the young man. According to Button, he gave her multiple stories about how her son arrived at his house, including he was dropped off as well as he went to pick him up. The boy also refused to explain why he had sent Lisi money on the teenager and Knight’s trip south, Button says.

Button then spent days searching for her son in the area, but she was never able to find any sign of him or learn why he went to Tennessee in the first place.

It would take over four years for more substantial evidence to emerge. In July 2016, a tip led police to the pickup truck Lisi was driving when he went missing. The vehicle was found stripped down and dismantled at a home in Franklin. “I just felt like the floor had dropped out from underneath me,” Button says of learning the news. “I did not expect the police to be calling me and telling me that they had located that vehicle. I just remember feeling, if someone did that to that truck, what in God’s name did they do to my son?”

Police have not released any details about who owns the property where the vehicle was found, but they did disclose Lisi was associated with people who were staying there.

After the truck was located, Button said she discovered two people involved in the truck’s dismantling had died. Other potential witnesses who may have had information, including Robbie Knight, his father and his brother, are now also gone.

The Tennessee Bureau of Investigation took over the case in November 2017, and agents believe there are people in the Franklin area who could still help crack the Lisi case.

“If he were alive, he would have contacted us,” Button told Dateline about her son in 2021. “It was just natural for us to keep in touch.”

“I know in my heart that he’s gone,” she continued, “but that doesn’t mean we have stopped looking for him. He’s out there somewhere and he needs to be brought home. He doesn’t deserve to be thrown out like discarded trash. He deserves peace. And his family deserves peace.”

Anyone with information about Nieko Lisi’s possible whereabouts or the case is urged to contact the Tennessee Bureau of Investigations at (800) TBI-FIND, or submit an online tip by emailing TipsToTBI@tn.gov.

For more on this case, stream Still A Mystery: “Unseen Enemies” on Max.