DENVER (CBS4)– The trial for a man who shot and killed an RTD security guard nearly one year ago continued on Wednesday.

On Tuesday, the defense for Joshua Cummings admitted he was the shooter.

Joshua Cummings (credit: Denver Police)

Cummings is accused of shooting and killing Scott Von Lanken, a security guard with the Regional Transportation District near Union Station.

Scott Von Lanken (credit: CBS)

The defense hasn’t tried to deny that Cummings was the gunman because of ballistic evidence, surveillance footage and multiple witnesses. What they are trying to prove is that Cummings didn’t plan to kill Von Lanken and shouldn’t be convicted of first-degree murder.

Von Lanken was working the night shift at Union Station when two women stopped to ask for help.

(credit: CBS)

(credit: CBS)

One of the women Von Lanken was helping testified Tuesday morning that Cummings held a gun to his head and said “Do exactly as I say.” Cummings shot and killed Von Lanken a few seconds later.

The defense is trying to argue that the statement “Do exactly as I say” doesn’t indicate premeditation.

Days after the shooting, he told CBS4’s Rick Sallinger he pledged allegiance to the Islamic State.

If the defense can convince the jury that Cummings didn’t plan to kill that night, he will face a lesser charge of second-degree murder.