In a music video for his song "Half a Tikket", Milwaukee rapper who goes by Mathboi Fly, spews explicit and violent lyrics while wielding an assault rifle. Throughout the video, he and another rapper are spotted with their guns equipped with high-capacity magazines, waving them around and even appearing in one scene to discharge one of them.
In November of 2021, an assault would be carried out using a weapon that appears in this music video. However, the weapon used in this terrible attack wasn't one of the firearms that Mathboi Fly had waved around while filming his music video- in fact the weapon itself wasn't even a gun-- the true murder weapon was the red SUV in the background. The SUV that would be reported by officers to "drive in a zig-zag pattern" in an "intentional act to strike and hurt as many people as possible." 
While Brooks' rap video would later be introduced as evidence during his trial, to prove that he owned the same make and model of car as the one used to commit a murder, something else in this video disproved one of Brooks' main arguments.
In this video, rapping under the name Mathboi Fly - Brooks demonstrated that he understood the concept of right and wrong when it came down to committing crimes- thus contradicting his mother's claim that he is not mentally stable and did not know what was happening. In an interview with Fox6, Dawn Brooks says [that] "he was not in his right mind and wasn’t intentional. "He didn’t mean to hurt nobody." His mother further discussed when [one is] "manic and out of control, you don’t know what you’re doing." before reiterating that, "[h]e didn’t know what he was doing. He wasn’t in his right mind."
In fact even before the trial, she sent an eight page handwritten letter to Judge Dorow. In the letter she explained that [Brooks was] "not stable mentally enough to fully understand the big mistake he [was] making by wanting to represent himself... he doesn't understand",
However as she finished the letter with "P.S. I know that he will not be happy that I wrote you and become angry I hope one day he'll understand that I did it out of love." her words show that he has, at the very least, an understanding of the concept of wrong and being wronged. He not only understands, but also responds to the idea of his being wronged and reacts with anger.
P.S. I know that he will not be happy that I wrote you and become angry I hope one day he'll understand that I did it out of love.
In classic case of self-incrimination, Brooks demonstrates understanding of what defines a crime through own lyrics. In his songs like "No Safety", "Westside Jumpshot", or "X", Brooks raps metaphors and euphemisms- in addition to violent and offensive expletives. The use of figurative language usage proves that he has an understanding of the concepts he himself. 
While his family says he is mentally ill and should be excused for his violent actions; the way he uses crime-based metaphors and similes illustrates he understands what crime is and what constitutes a criminal act.
1.Kay Jones, Jason Kravarik and Travis Caldwell, CNN, November 24, 2021. Waukesha parade crash suspect appeared to have no emotion as officers tried to stop him, authorities say. https://www.cnn.com/2021/11/24/us/waukesha-car-parade-crowd-wednesday/index.html
2. Melogno S, Pinto MA, Badolato F, Sist E, Esposito A, Orsolini M, Tarani L. High-level language competencies and Theory of Mind in a group of children with Klinefelter syndrome. Am J Med Genet A. 2019 Feb;179(2):183-189. doi: 10.1002/ajmg.a.12. Epub 2019 Jan 8. PMID: 30618195.