For about 15 years, Uriel Rincon told authorities he didn't recognize the gunman who he saw kill Run-DMC's Jam Master Jay in the rap star's recording studio.

But on Wednesday, Rincon — who was himself wounded in the gunfire — pointed across a courtroom and identified Karl Jordan Jr. as the shooter in one of world's most infamous killings in hip-hop history.

“He kind of walked directly to Jay and gave — like, half a handshake, with an arm. And at the same time, that's when I hear a couple of shots,” Rincon told jurors of Jordan.

Both Jordan and Ronald Washington, who's accused of being an accomplice, have pleaded not guilty.

Rincon said he was looking down at his ringing phone as the gunfire erupted, then looked up again.

“And then I see Jay just fall,” he said.

Then, Rincon said, he felt pain in his left leg and realized he'd been shot and that Jam Master Jay — the hip-hop luminary who'd hired him as a teenager to help around his studio and record label — was gravely wounded.

“I'm trying to tend to my wound, and at the same time, I'm trying to give Jay attention — asking him is he OK? Can he talk? Whatever — and he is just not responding," Rincon testified.

He said that during the shooting, Washington was at the studio door, telling another witness to get on the ground and stay there.

Rincon was the first eyewitness to testify in the long-awaited trial, which comes over 22 years after the death of Jam Master Jay, born Jason Mizell. The DJ helped rap gain a wider audience through his role in Run-DMC, the 1980s powerhouse group that notched the genre's first gold and platinum albums and was known for such hits as “It's Tricky” and its take on Aerosmith's “Walk This Way.”

Jordan, who was Mizell's godson, and Washington, a childhood friend of the DJ, were arrested in 2020. Prosecutors say the two had been planning a cocaine deal with the rap star and killed him because they were about to get cut out.

Washington's lawyers have said authorities had no clue who killed Mizell and that they brought a case held together only with “tape and glue."

Jordan’s attorneys have said he was at his then-girlfriend’s home at the time of the shooting. One of the lawyers, Mark DeMarco, emphasized while questioning Rincon Wednesday that the witness repeatedly told investigators for years that he hadn't quite seen and couldn't identify the gunman.

“I was confused and scared and not trusting a lot of things that were happening," Rincon said, explaining that he'd struggled to fathom what had happened.

“I didn't understand what I saw, and I didn't understand why or who — because, again, it was somebody I knew. So that's why it was hard for me to grasp,” he said.

He finally named Jordan and Washington to authorities around 2017.

When asked why he finally did so, Rincon said he thought of Mizell’s surviving family.

“I felt that his wife and his children needed closure, and I felt that they should know what took place,” he said.

The trial opened Monday, and on Tuesday, Brooklyn Federal Judge LaShann DeArcy Hall ruled that Jordan's rap lyrics — which include first-person accounts of violence and drug dealing — can't be used against him at trial, as prosecutors sought.