(CNN) Antwon Rose II, the 17-year-old who an East Pittsburgh policeman fatally shot in the back as he fled a traffic stop, was no common thug and is not on trial, his mother wrote in a letter to prosecutors.

"He was a rose that grew from concrete," Michelle Kenney said of her youngest child. "Despite darkness all around him, he was kind, loving and funny. The smile that emanates from photos of him truly reflects who he was."

Antwon Rose was "very smiley" and loved goofing off with younger kids, a former employer says.

Kenney conceded in her letter that she knows nothing of trial strategy, but she knows it's important that jurors in ex-officer Michael Rosfeld's trial , which began Tuesday, understand her son's character.

Allegheny County prosecutors Daniel Fitzsimmons and Jonathan Fodi, the recipients of Kenney's letter, are handling the criminal homicide case against Rosfeld. His defense attorney on Tuesday told jurors to ask themselves what a reasonable officer would do in the same circumstances and called Rose an "accomplice" in an earlier drive-by shooting.

Following a drive-by shooting in June in nearby North Braddock, Pennsylvania, the 30-year-old policeman pulled over a car that matched a description from the drive-by.

Antwon was in the car. Unarmed, he ran. Rosfeld opened fire, hitting the teen in the face, right arm and back, court record show. Evidence suggested Antwon was not the gunman in the previous shooting, and Rosfeld made inconsistent statements about whether he believed Antwon had a gun, records show.

The shooting sparked widespread protests in Pittsburgh and the surrounding area.

Mother knows she's been hard on DA's office

"As I sit through the trial and the defense discusses the dangers of the community in which Antwon lived and the criminal element that surrounded him -- even the allegations of criminal involvement on the day he was killed -- I am reminded of just how unique he was and will always be to me and those who knew him best," his mother wrote.

She thanked Fitzsimmons and Fodi for their work and patience, and she apologized for the times she has directed her frustrations at the Allegheny County District Attorney's Office.

JUST WATCHED Antwon Rose's mom breaks down in interview Replay More Videos ... MUST WATCH Antwon Rose's mom breaks down in interview 02:47

Acknowledging her bias as the boy's mother, she vowed to defend his legacy and memory. Every mother thinks her child is exceptional, she acknowledged, but she is not the only one who feels this way about Antwon.

"Quick-witted and hilarious, his friends also say he was one of the best of skiers they knew. He taught the kids in our neighborhood to roller blade, skateboard and even gave the kids his own roller blades and skateboards to use (only for me to replace!)," Kenney wrote.

"I always wanted Antwon to know how much I loved him and now I realize how much he was loved by so many in the community."

'How could anyone hurt this kid?'

Following the shooting , others acquainted with the young man backed Kenney's characterization. The Woodland Hills School District, where Antwon was in a program for gifted students and took honors courses, called him a generous and promising student.

"He had this million-dollar smile," Assistant Superintendent Licia Lentz said at the time. "He was gifted and teachers were really trying to mentor him."

Gisele Barreto Fetterman, who owns the Free Store in Braddock, where her husband was mayor, said Antwon volunteered at the shop during the summer of 2015 and regularly dropped by on Saturdays. She described him as an attentive, mature young man with "such great energy."

JUST WATCHED Protesters rally over police shooting death Replay More Videos ... MUST WATCH Protesters rally over police shooting death 01:34

The store provides food, toys, clothes, backpacks and other items to members of the community, and Antwon would offer to entertain kids while their parents picked up what they needed, she said.

"He was just a really great kid. He had these really intense, big eyes. He was very smiley, very goofy," Fetterman said shortly after Antwon's death. "I think about how his life was cut short and all the things we won't see him do and all of the dreams we will never see him achieve and it's a really sad day."

Antwon counted basketball, surfing, skating, jazz saxophone and volunteering among his interests, according to his funeral program . Referring to him as "one of our skaters," the Switch & Signal Skatepark in Pittsburgh posted an Instagram remembrance saying that video from the shooting "shows a scared kid running for his life."

"How could anyone hurt this kid, feel threatened by him, see him as a threat? It's baffling and sad but the world we are living in sees Antwon as a threat because he was a black boy in a car," the post said.

'Friendly, goofy and fun'

Friends, family and teachers described Antwon as hardworking. He took his first job at a gymnastics club and then at two pizza parlors. One of his friend's parents recalled how he used to bring his pals pizza after work.

Kimberly Eads Ransom, who owns Pittsburgh Gymnastics Club where Antwon worked in 2015 and 2016, fondly remembered "Mr. Antwon" chasing kids with pool noodles and joining them for bounce sessions on the trampoline.

JUST WATCHED Teen shot by police after running from car suspected in a shooting Replay More Videos ... MUST WATCH Teen shot by police after running from car suspected in a shooting 00:44

"He was friendly, goofy and fun," Ransom said in June in a Facebook post . "When I worked with him, he had big plans and dreams and was a people pleaser. My favorite memory of him is when he showed up in a full suit in the sweltering heat for his gym job interview. I hired him on the spot."

It is these sort of memories that Kenney implored the prosecutors to impart to jurors as Rosfeld's trial proceeds, she wrote.

"They deserve to know the real him. The defense has tried to make him out to be 'just another thug,' but please let the jury know who he really was," she pleaded.

She closed saying, "I truly believe the two of you are just as committed to getting justice for Antwon as I am, as my family is and all of the lovers and supporters of justice for Antwon are! I thank you for understanding my overbearing, protective and sometimes bossy nature. What makes me proudest in life is that I am, and will always be, Antwon's mom."