Watch CNN's "AC360" at 8 p.m. for more of the interview with Michael Brown's parents.
(CNN) -- Twelve days after her son died -- a period marked by large, emotional protests but not the arrest of the police officer who killed him -- Michael Brown's mother didn't have faith in authorities.
But one day after meeting with Attorney General Eric Holder, the top law enforcement official in the country, Lesley McSpadden held out hope that she'll eventually believe in those investigating her 18-year-old son's death.
"Just hearing the words come directly from (Holder's) mouth, face-to-face, he made me feel like, one day, I will," she said Thursday in an interview -- alongside the late teen's father, Michael Brown Sr. -- with CNN's Anderson Cooper. "I'm not saying today, or yesterday, but one day, they will regain my trust.
"But first I have to get to where I'm wanting to get to. And we haven't even begun."
Holder came to Ferguson, Missouri, on Wednesday to check in on the federal civil rights investigation into Brown's shooting as well as to talk to leaders, citizens and others in the middle of the prolonged, tense situation.
He met privately with Brown's parents, promising them "that it will be a fair and thorough investigation," according to McSpadden.
"You can read a person. And when you're looking at them and they're looking at you in your eyes, it puts some trust back there," she said.
That said, federal authorities aren't the only ones looking into the shooting. Plus, they have a higher standard than locals who are on the case, since the civil rights investigation requires proving that Ferguson police Officer Darren Wilson exhibited "racial hostility" -- as explained by CNN senior legal analyst Jeffrey Toobin -- in the shooting of Brown. Wilson is white; Brown was African-American.
The case is more straightforward for the St. Louis County Prosecuting Attorney Robert McCulloch's office, which began presenting testimony in secret to a grand jury Wednesday. Those grand jury proceedings -- which McCulloch said could continue into the fall -- could lead to an indictment against Wilson.
"(We want) this guy to go jail, so we can have some type of peace," Michael Brown Sr., said. "(Wilson) is still walking around with pay; it's not fair to us.
"... We're hurt. And I can't tell what (Wilson) is doing, but he has his life. Our son is gone."
Many Brown family supporters have demanded that McCulloch be taken off the case, given his relationship with the African-American community and their claims that he is biased toward law enforcement.
McSpadden has said that she did not believe that those those pressing her son's case will be able to achieve justice as she defines it -- with Wilson being charged in her son's death.
"Up until yesterday, I didn't," she said, crediting Holder with helping change her views.
That doesn't make it easier to accept Michael Brown's death.
Her son "was a teenager (who was) growing up, (who should have) had a chance to make a mistake and correct it, just like the officer," Lesley McSpadden said.
"... You had a choice, and he chose the wrong one. Was it really necessary? No. My son was only 18. Only 18."
She added later of her son: "He was special to me. He was ours. He was peaceful. He was humble. He didn't ask for that, he didn't deserve that, and it was wrong."
The parents expressed appreciation for those who have taken to the streets of Ferguson to support them, while criticizing those responsible for looting and violence for "doing nothing but causing more pain plus it's shaming his name," Brown Sr. said.
"If they're not for the cause, they need to just go back to you regular life, go back home to your family. Hug your son, hug your daughter, love our loved ones."
All things he'll never be able to do with his son again.