It’s been 12 hours since an alleged gang shooting in Downtown Brooklyn and Detectives Jason Cuttler and Lucas Huertas, of the Gun Violence Suppression Division, are pouring over surveillance video they obtained.

"The first step is to see if they go into that train station," said Huertas.  "And then we’ll go from there," said Cuttler.

“It seems this is where they may have been spotted by the rival group," said Huertas, as he reviewed video of the surveillance video, obtained from a nearby store.

"There he goes. He’s got the gun in his hand. He takes a shot, and then he goes down. The shooter comes here, stands on the corner and starts shooting this way towards this group of kids."

The Gun Violence Suppression Division uses social media and police databases to track gang members across the city in real time.

"We’re at 1,287 alerts, case subjects and their associates," said Detective Brian Ellensohn.

"We have to make sure that with everything we do, that we go above and beyond to make sure we get all of our evidence gathered, and tell a story that people can see beyond any doubt we have the right person for the right crime," said Huertas.

They drive to the 84 Precinct to confer with detectives who are working the case simultaneously and emerge with an I.D. of the alleged shooter, an alleged member of the Young Savages set of Folk Nation.

They also learn a victim of the shooting, a teen treated at Kings County Hospital with a gunshot wound, is the alleged gunman’s younger brother.

"Did the shooter wind up going to the hospital to see his brother?" we asked.

"That’s what we’re trying to figure out. Our detectives out in the field spoke to the detectives from the 84th Precinct and we come to find out that he did end up at Kings County Hospital," said Cuttler.

"They’re saying that the shooter may have changed clothes so they’re going to review the footage themselves and get a more accurate description of what he’s wearing now and track him from when he leaves the hospital," said Huertas.

The detectives spend several hours going to businesses near Kings County Hospital looking for surveillance video.

"It couldn’t have worked out any better," said Huertas as he returned to the unit's headquarters.

A surveillance camera near the hospital captured the images the detectives were waiting for.

"We see him get on a train and we see him get off a train," Huertas said.

“He's wearing the same chain that he was wearing when he was running when he had the red hoodie," said Cuttler.

Two days later, detectives obtained a search warrant for the suspect's home.

"This is a three-story brownstone, the father owns the entire building, when we make entry just be mindful that there could be other people in there," said NYPD Lieutenant Richard Zacarese.

Check back on NY1.com for the third part in this exclusive series.