Internet sleuth who once body doubled for J.LO tracks down cruel killer who slew dad 26 years ago – earns praise from top cop!

As previously reported actress Joselyn Martinez was just 9 when her beloved father was gunned down outside his New York City restaurant in 1986.

Cops quickly identified the suspect as 16-year-old Justo Santos, but the teen appar­ently fled to the Dominican Republic and disappeared. Detectives spent years in a futile search for him, then the trail grew cold and, eventually, the case was all but forgotten.

Joselyn – who served as a stand-in for Jennifer Lopez in the 2009 film “The Back-up Plan” – couldn’t forget. In 2004, she started scour­ing the Internet for clues about the man who had allegedly murdered her father in cold blood. And in­credibly, 26 years after her father’s death, she finally found him.

Thanks to Joselyn’s tireless cyber-sleuthing, Santos was arrested on June 6 and charged with the brutal crime.

“I felt I had to do it for my father,” said Joselyn, now 36. “I was determined to bring his killer to justice.”

Authorities say that on Nov. 22, 1986, Santos and two friends walked into Dominican Express, the restaurant Joselyn’s father, Jose, owned in Manhattan, and began verbally and sexually harassing Joselyn’s mother, Idalia. Jose tried to kick the group out, but an argument ensued. Cops say Santos pulled a gun and shot Jose right in front of Idalia.

“He ruined my life. He ruined the life of my daughter,” Idalia said of Santos.

Although Santos was identified the following day, he eluded ap­prehension by fleeing the country.

“I saw his picture on the wanted posters,” said Joselyn, who lives in the Bronx. “He was smiling. My mom told me to never forget his name.”

She didn’t.

For nearly a decade, Joselyn spent hour after hour scrolling through sites like MySpace, Facebook and looking for Santos.

“I couldn’t let it go,” said the actress. “I knew he must have thought he’d gotten away with it, and that made me even more determined to find him.”

Joselyn admits there were times she felt like it was a hopeless endeavor. But in February of this year, she finally got a hit.

One of her searches led to a man named “Justo Santos” in Miami – and he had the same date of birth as the accused killer.

“I thought, ‘I’ve got him. I’ve finally found him.’ I was so excited,” she recalled.

The information Joselyn pro­vided to police was exactly what they needed to make an arrest. Santos was taken into custody in Miami and confessed to the killing. New York’s top cop had nothing but praise for Joselyn’s detective work.

“I applaud her,” said police commissioner Ray Kelly. “It’s ad­mirable what she did. She made a concerted effort and it paid off.”

Joselyn added: “Now my family and I have some peace of mind knowing that my father’s killer is not still out there.”