Jarrett Robison, who is now 20 years old, is charged with killing Scott Hardin, a father of two. It was just before Father's Day weekend of last year.
Charlene Hardin-Argo hadn't heard from her brother and began to worry.
"The more phone calls I made, he wasn't calling me back, so I knew something was wrong," she said.
READ MORE: Houston family searching for answers 2 months after father's murder
Then, investigators found the truck Hardin was driving with blood inside.
The next day, they found Hardin's body in a grassy area, more than eight miles away. From that moment, his sister was on a mission to find his killer.
"He was my brother," she said. "He needed justice. Somebody had to advocate for him."
So she stayed in contact with detectives, and began conducting her own research.
"I spent two or three hours a day. I stayed on the phone with them daily," said Charlene. "If I wasn't calling them, I was texting them."
She says she spoke with dozens of people, one after another.
"Every time I would turn a corner, it showed me to another corner," said Charlene.
Then suddenly, she noticed something she says helped open the case. She began conducting more research on Robison. He was arrested days after her brother's murder, on a different charge.
"I saw that he was arrested with a gun," recalled Charlene. "So, I called the detective and I said, 'Hey, have we checked that gun to see if that's my brother's?' and in the end, that's probably what started the big case because it was my brother's gun."
The evidence began adding up.
Court records say Robison's DNA and fingerprints were found inside of Hardin's truck.
Investigators say Robison also exchanged a ring that Hardin was known to wear for money at a pawn shop.
Charlene credits Houston police detectives, like HPD Detective Terry and HFD Arson Investigator Bruce for their efforts, too.
"They didn't tell me once, they told me three times: You're the reason this is happening," said Charlene. "So, the more they told me, 'You're the reason,' the more I wanted to do. So they welcomed my help."
While Charlene is grateful there are charges, she says the case isn't closed yet. She says there's more to come.
"It's not over yet," she says. "Still got to seal it."
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