Gary Russo, 2nd Avenue Subway Sinatra, missing in New York City

A New York City construction worker who became famous for his lunchtime crooning near the 2nd Avenue subway line has been missing for nearly two weeks.

Gary Russo, 54, rose to fame several years ago after he began singing near his job site on the Lower East Side in Manhattan. Russo, who earned the nickname 2nd Avenue Subway Sinatra, would set up a mic and sing for passersby in his construction uniform and hard hat.

Behind him, a sign read: "Forget all the noise, traffic and the impact of the 2nd Ave subway. Enjoy the music. Hard hats + microphones."

A video of him singing Frank Sinatra's Summer Wind was posted to YouTube in August 2011.

Russo called it "little noon concert."

"We're trying to give back a little bit, you know, lunchtime," he can be heard saying in the clip.

That video racked up more than one million views in the weeks after it was posted.

Russo seemed to capitalize on the internet fame. He gave a series of interviews in U.S. news outlets, and even in Germany and Japan. He co-wrote a book, Don't Die With Your Song Unsung, and announced an upcoming CD. He performed at the Blue Note jazz club in New York and at the starting line of the New York City marathon.

His construction-site shows stopped shortly after those performances, The Associated Press reported, because he was transferred to another site and the act didn't fit in there. However, Russo continued performing at the marathon and other venues every once in awhile.

More recently, he appeared to have been building a "house boat/office studio" to house two boats in Sheepshead Bay, Brooklyn, according to some of his Facebook posts.

He appeared to be excited about the project, giving regular updates. "Good day today," he wrote in April. "People at the marina are so willing to lend a hand. A great community of people."

Missing since July 28

Russo, a father of two, left his house in the Howard Beach neighbourhood of Queens shortly after midnight on July 28 and has not been seen by friends or family since then, The Associated Press reported. The detective squad of the 106th precinct in Queens is looking for Russo, according to a missing person's poster from the police department.

"I just want to know that he is OK, please and thank you!" wrote his daughter, Amber, on her Facebook page, where she also requested help locating her missing father

Amber Russo wrote on Aug. 4 that her mother found her father's truck in Howard Beach and that family and friends had organized a search party to look for him.

Russo's friend Apryl Nebozenko, who sometimes performs with Russo, told The Associated Press that he seemed uncharacteristically down and drained at a gathering at her home in mid-July. She said he seemed more upbeat when they spoke again about a week later.

Nebozenko started a crowdfunding campaign to help cover the expenses of a private investigator who is helping the family locate Russo pro bono.

"We are concerned that he needs medical attention and needs to be found ASAP," Nebozenko wrote on the GoFundMe page she set up.

The family has put up missing person posters with Russo's picture and has been sharing them on social media.

Others have also been sharing his image online to help with the search.

Russo has not tweeted since March 5, when he said: