A witness who tried to save Alex Pretti collapsed during the attack, recounting the final moments of the ICU nurse—what she saw before the shooting—horrified and outraged his family on behalf of their son…

Alex Pretti, the 37-year-old ICU nurse shot and killed by federal officers in Minneapolis, is being remembered by one of his colleagues as a ‘kind guy’ and a “very, very skilled nurse.”

“He was energetic, he was kind. He was always quick to have a joke or a laugh,” Dr. Dimitri Drekonja, an infectious disease physician at the VA Medical Center where Pretti was employed, told PEOPLE in an exclusive interview.

“He was very capable. When he gave a summary of the shift … [he] had all the information at his fingertips. He would tell me how the family was doing. He was a very, very skilled nurse,” he continued.

Drekonja, 51, went on to say that the “biggest thing” he wants others to know about Pretti is “that this was a kind and helpful guy — and nothing over the years that I knew him contradicted that. He was always willing to help. Whether it was a small task, whether it was patient care, whether it was, ‘Hey, I can give you a ride over, we’re gonna meet for drinks after work.’ He was just a really kind guy.”

“It’s just been gutting,” he continued of Pretti’s death, adding that he and other colleagues at the hospital “want people to know that [Pretti] was a good person. He was such a nice guy.”

Drekonja additionally said that he and Pretti shared an interest in mountain biking, and that they would often discuss their favorite local routes.

Pretti had been a registered nurse since January 2021, according to his nursing license, obtained by PEOPLE. He previously worked at the U.S. Department of Veterans Affairs.

Pretti was shot and killed on Saturday, Jan. 24, at about 9:00 a.m. local time.

“DHS law enforcement officers were conducting a targeted operation in Minneapolis against an illegal alien wanted for violent assault,” DHS assistant secretary Tricia McLaughlin told PEOPLE in

McLaughlin claimed that a man, now identified as Pretti, “approached” U.S. Border Patrol officers while armed with a handgun and “violently resisted” as they attempted to disarm him, saying an agent then fired “defensive shots.”