He was 15 when he was convicted of her murder.
He's now 17, learning Thursday that conviction was overturned on appeal.
"He's never going to get these years back. And the family has lost two children. We just hope they haven't lost two children for good," defense attorney Steve Plesser said.
The case from the tiny town of Valley Springs in Calaveras County garnered national attention. It was heard not by a jury, but by Judge Thomas Smith, because Fowler was a juvenile.
Smith found Fowler guilty, and ordered that he be detained until age 23, but the appeals court said statements made by Fowler during interrogations shouldn't have been allowed because he wasn't properly advised of his right to remain silent.
"And, although there was no confession, a 12-year-old being interviewed four times by police and FBI is at some point going to have inconsistencies," Plesser said. "And the court relied on those inconsistencies to find him guilty."
So what happens next?
Calaveras County District Attorney Barbara Yook declined to comment on Thursday, but a statement issued Friday from the sheriff's office said they are prepared to retry the case.
For the time being, Fowler will remain in custody, although his attorneys say they will likely ask for him to be released on bail if the case is indeed retried.
Those requests were denied during the first murder trial and Fowler remained in detention.
"Our client certain had no history of doing anything suggesting he was capable of that," Plesser said. "So whoever did that is a very dangerous and demented person, and very worried that they're out there and we're going to find out that they committed another crime."