MADISON, Wis. -

Madison police officers said they stand by Officer Stephen Heimsness’s decision to pull the trigger and use deadly force Friday morning.

The 15-year veteran of the force shot and killed Paul Heenan, who police said was approaching Heimsness aggressively and reaching for his gun.

Dan Frei is the president of the Madison Professional Police Officers Association. Heimsness is the treasurer for the union.

Frei, who has served 17 years on the Madison Police Department force, defended his colleague’s actions. He said in that kind of split-second decision, an officer has to quickly assess the danger and take action based on what the officer knows, no matter how little information that may be.

"We don't have the luxury of knowing what's going to happen in advance or you magically know what the person's mindset or intentions are," Frei said. "So we have to assume somewhat of a worst-case scenario based on what we know is realistic from our training experience."

The initial calls Friday morning were for a burglary in progress, according to police. Once officers arrived at the scene, it appeared that Heenan was fighting with a neighbor.

Madison Police Chief Noble Wray said Heenan approached Heimsness yelling and swearing, and then reached for his gun. That's when Heimsness fired three shots at Heenan, killing him, police said.

"Our training and probably even common sense tells us that there's only really one reason why somebody's trying to take our gun, which is to harm us," Frei said.

Frei said Heimsness only had seconds to process and react to the situation, and he made the right choice for his safety by pulling the trigger.

"In this situation, in a matter of seconds, you're trying to challenge somebody who you believe is a burglary suspect," Frei said. "And then you have the person progressing toward you, there's not a lot of time to kind of have an assessment of what's really going on here or, you know, even get a sense of who or what is going on with this person.”

Officer Kimba Tieu, who is in charge of training for the Madison Police Department, said officers are merited to use deadly force when they believe there is a threat of imminent death or great bodily harm to themselves or another person or persons.

"Until we know, again, especially in a high-risk situation, we're going to err on the side of caution and take something that we know to be more effective in those instances than something less effective," Tieu said.

Tieu said officers have a lot of discretion when considering the use of force at a scene. He said the use of any kind of force is judged on all of the factors that face an officer at a certain time and how he or she is able to perceive it in those moments. That could include the severity of the crime called in, the time of day, which would dictate the amount of light, the actions and words of a suspect, the proximity of a suspect to an officer, and the amount of time an officer has to make a decision.

"It would be inappropriate for you to try to clear a building, to try to deal with a suspect that you haven't cleared the hands, you don't have any stability in the scene yet, and it's all very new as the information is coming,” Tieu explained.

Tieu said officers do not have to carry Taser guns. In fact, there are not enough of them for everyone on the patrol force to carry one at all times. Officers can sign them out at will, and most of them are trained to use them.

While it is unclear whether or not Heimsness had a Taser gun the night of the fatal shooting, Tieu said it would have been inappropriate to use one considering the circumstances.

"It's not a natural thing for people to arm themselves in the presence of a uniform, in particular a uniformed police officer," Tieu added.

Tieu added that Madison police policies require that any officer using a Taser gun on a suspect who may be armed must have "lethal force coverage," meaning another officer has to have his or her gun drawn and pointed at the suspect to ensure their colleague's safety.

"I'm absolutely confident that Officer Heimsness used the correct judgment and everything that happened was unavoidable," Frei said.