The only non-terrorism related homicide reported on 9/11 remains unsolved to this day.

Henryk Siwiak, 46, a Polish immigrant with a wife and two children, was shot and killed in Brooklyn on September 11, 2001. He was on his way to clean a supermarket and found himself on a violent corner of Bed-Stuy at 11:42 pm.

Fifteen years later, authorities have yet to name a suspect or a person of interest in Siwiak's death.

On any given day, six to eight detectives would have responded to the scene. But on that day, only one came to the intersection of Albany Avenue and Decatur Street, where Siwiak was shot.

Henryk Siwiak, 46, a Polish immigrant with a wife and two children, was shot and killed in Brooklyn on September 11, 2001

That was the only homicide reported in New York City outside of the 9/11 attacks. Siwiak's sister Lucyna is pictured holding a photo of him

'We would have had uniforms canvassing the area, we would have had computer checks running, we would have had all the forensic capabilities available,' former lieutenant Tom Joyce told NBC News.

That sole detective took only one Polaroid photo.

Siwiak was not supposed to be in Bed-Stuy that night. He had just picked up a job cleaning at a Pathmark supermarket in Flatbush, for about $10 an hour.

His wife, Ewa, their daughter Gabriela and their son Adam were still living in Krakow. Siwiak had moved to the United States 11 months earlier looking for work.

Siwiak was not supposed to be in Bed-Stuy that night. He had just picked up a job cleaning at a Pathmark supermarket in Flatbush (pictured), for about $10 an hour

After ending up three miles south of his intended destination, Siwiak was fatally shot at the intersection of Albany Avenue and Decatur Street in Bed-Stuy (pictured)

'I told him just in case: don't leave tonight, because it can be dangerous in New York,' Ewa told WNYC in 2011.

But Siwiak, who sent money to his family, went to pick up his shift regardless.

The Pathmark supermarket was on Albany Avenue, but Siwiak ended up three miles south in Bed-Stuy.

'He just got off the train at the wrong block and at the wrong time. He's a totally innocent individual,' retired detective Mike Prate told NBC News. 'It was really a shame.'

The area, Prate said, was rife with gang shootings, robberies and narcotics.

'Everything else in the city shut down. It didn't seem like anything on that block shut down,' he said.

Prate made several forays into the case until he retired in 2012. It remains open and other detectives are now working on it.

'It's just a matter of finding the right guy with the right information,' Prate said. 'There is a person out there who saw, knows, or heard about it.'