AURORA, Colo. -- The man accused of gunning down an Aurora police officer for what sources say is a racially motivated shooting made his first court appearance Thursday afternoon.

Police said Brian A. Washington, 27, of Denver walked up to the car of Detective Mike Thomas and opened fire. The shooting occurred just after noon at the intersection of Peoria Street and Montview Boulevard on Wednesday.

Aurora police have not officially given a motive for the shooting. However, sources close to the investigation told 7NEWS that the shooting was racially motivated, according to items found during a search warrant.

Police don't believe Washington knew Thomas -- nor the fact that he was a police officer -- but they are confident that they have the right man.

"The best thing to do is to hold the person who did this accountable," said Aurora Police Chief Dan Oates. "So we will not be prepping this case in the press or trying this case in the press. This matter is really in the hands of the district attorney at this point and I will not be commenting on evidence or answering questions about the case."

Oates held a second meeting for the police force to update officers on the case so they can feel confident the case is moving forward.

In cuffs and wearing a jail jumpsuit, with baggy pants hung low on his bottom, Washington showed up in court Thursday and uttered a few words as he was advised of his rights. He is being held in segregation at the Adams County Jail because of the charges against him. He faces first-degree murder and is being held without bond. It is likely the district attorney will seek the death penalty, 7NEWS reported.

Police are not allowing the media to show Washington's face because they still must complete a photo lineup for another shooting that Washington is suspected to be involved in.

Washington has a significant criminal history, including weapons and drug possession charges, and was being sought by Denver police for a shooting that occurred Monday night at 33rd Avenue and Pontiac Street. In that Sept. 18 incident, a woman sitting inside a car was shot at but not hit. Police still need to complete a photo lineup in the case.

Washington's next court appearance is Monday, Sept. 25, at 1:30 p.m. A gag order in the case has been denied.

Good Samaritan Describes How Washington Was Apprehended

Washington was arrested minutes after the shooting with the help of citizens, another officer and two corrections officers.

Denver resident Paul Brandin, 51, said he was waiting to make a left turn at the intersection when he saw people tending to a driver in the blue car right next to him.

"I thought the guy had just had a stroke or heart attack or something," Brandin told 7NEWS.

Then he saw another pedestrian, who turned out to be Washington.

"He walked right in front of my car, and I had to hit my brakes to keep from running him over, and he kept insisting he was an officer, he was an officer," Brandin said.

Brandin said he saw that the man had a gun.

"He got by the window and I see the gun. Stupid, stupid thing, but I had to get out of the car and try to help," he said.

By the time Brandin got out of his vehicle, the suspect and several other men were wrestling. Brandin said the suspect dropped the weapon on the ground.

"And I stepped over and kicked it with my heel up underneath the car so nobody could get to it," he said.

And he guarded the gun until police arrived. He said he doesn't know what prompted him to get out of the car and jump into a volatile situation.

"Stupidity, I don't know. I wouldn't have done it now, thinking about it. It's just reaction. It just all happened so fast," Brandin said.

It wasn't until later that he realized what he'd done and what had happened right in front of him.

"I don't think I'll ever try anything like that again. It was too scary of an experience," he said. "I was in the wrong place, wrong time."

Brandin said a plainclothes Department of Corrections officer who helped subdue the gunman is the real hero but said that when uniformed officers arrived, they thanked him for his efforts.

Colleagues Remember Thomas

Although Thomas was not in uniform at the time of the Wednesday shooting, he was technically on duty when he was killed, police said. Oates said Thomas was moving from one training site to another and was about to switch vehicles. Oates said Thomas was shot at least once, with a bullet entering his left side. He was pronounced dead at University Hospital.

Thomas had been a K-9 officer and a narcotics officer before he was promoted to detective in April 2005, working in the 3rd District. He was a highly decorated officer who had received more than a dozen awards, including the Medal of Honor from the Aurora Police Department.

The police chief said Thomas was "among the hardest working detectives" and irreplaceable.

His fellow officers said he was a kind, compassionate person who, just before Christmas, gave a $100 tip to a waitress who was having a bad time.

"That was the kind of person Mike was. My wife and I were working through a vehicle problem and he's like, 'Do you want my car?' So, he's just very generous," said Officer Lance Dyer.

"After 24 years in the business, my biggest thing is for people to understand that we're human beings too. We bleed, we suffer. We're victims. Mike was a victim yesterday, so we feel the same things they feel when something like this happens," said Aurora police Officer Steven Sopata.

Police spokesman Bob Friel said Thomas' death was the first in the line of duty for the department in 19 years. Edward John Hockam was killed on Sept 21, 1987. Thomas is the fourth Aurora officer to die on duty.

Thomas is survived by family, including a daughter in her 20s. Officers have set up a memorial fund to help Thomas' family. Donations can be made to the Rocky Mountain Law Enforcement Credit Union.

Thomas' funeral will be held Tuesday, Sep. 26 at 11 a.m. at the Heritage Christian Center in Aurora.