McClendon, who worked for the Massachusetts Department of Corrections, is now in custody at the detention center in Cullman County, Alabama, Deputy Chad Whaley confirmed to The Daily Beast.

On Sept. 11, 1988, Tremblay went with her mother and her mother’s boyfriend to the LaSalle Social Club in Lawrence, Massachusetts, about a 20-minute drive from their home in Salem, New Hampshire. At some point during the afternoon, Tremblay went outside to play while the adults enjoyed themselves in the club. They never saw her again.

Following a frantic search of the area, Tremblay’s mother and her boyfriend reported her missing. The little girl’s body was discovered the next day. Investigators questioned “scores of witnesses, suspects, and persons-of-interest” over the ensuing weeks, months, and years, Blodgett said.

Then, the case went cold.

In 2014, a team of assistant district attorneys and state police detectives specializing in unsolved crimes redoubled their efforts in the Tremblay case, according to the Essex County DA’s Office.

Investigators learned that McClendon had been living in Chelmsford, Massachusetts, about 16 miles from Lawrence, at the time of Tremblay’s murder. He moonlighted as a carpenter, and “worked and frequented establishments in the city of Lawrence including the Seventh Day Adventist Church on Salem Street,” the DA’s office said in a press release. Evidence recovered from Tremblay’s body was “instrumental in solving the case,” it said.

McClendon “has been a person of interest for a period of time,” Blodgett told reporters.

In an email, Essex County District Attorney’s Office spokeswoman Carrie Kimball told The Daily Beast that she was unable to comment further on the specifics of the evidence that provided the break in the case, but that more detail would be given at his arraignment.

Tremblay, who was a 6th-grader at the Lancaster School in Salem, New Hampshire, at the time of her death, is “forever going to be 11-years-old,” Ganley, who has for years pressed authorities to solve her friend’s murder, said in a phone interview on Wednesday.

Ganley, who was four years younger than Tremblay, told The Daily Beast that she has experienced “a rollercoaster of emotions” since learning of McClendon’s arrest.

“I was initially very shocked,” Ganley said. “I’m still in shock. This day is really here, and it’s really happening. We always hoped for this day to happen… There are times you lose hope, but I want other families and other friends who are the victims of what is now called a ‘cold case’—don’t ever give up hope.”

Notorious serial killer Tommy Lynn Sells, who confessed to 13 murders in seven states and was executed by lethal injection in 2014, was at one point eyed as a potential suspect. But the rail-riding carnival worker was later cleared, and detectives kept hoping for a solid lead.

Ganley said she had never heard McClendon’s name before the public announcement of his capture, and that investigators had never brought him up previously.

“Even though it is a rollercoaster of emotions, and grief and sorrow and happiness that somebody will be held responsible, it is shocking that he was a churchgoing correctional officer,” Ganley said. “The fact that he was a member of law enforcement never occurred to any of us.”

Over the years, Ganley said she always wondered who could have killed her friend so callously.

“People don’t just kill one child when you’re a predator,” she said. “It wasn’t an uncle or a parent or anything like that, so what type of person would do this? How did she cross his path? Was he watching her? Did he stumble upon her that day? Are there other families out there waiting for closure? There are a lot of questions yet to be answered.”

McClendon’s arrest obviously doesn’t bring Tremblay back, Ganley acknowledged. But, she explained, seeing him in handcuffs opens the door for what she defined as a second stage of the grieving process.”

Tremblay “touched a lot of lives,” said Ganley, adding, “Everybody in school knew Missy.”

“Her mom passed away several years ago, her father was very uninvolved [and] I don’t know if he’s still alive or not,” Ganley explained. “I know there is a cousin… I share their grief. I’m happy that they have closure, I’m happy for all [of Tremblay’s] friends. People of all ages, her friends, all of the school staff, the Salem Boys and Girls Club—everybody’s lives were affected by this.”

As for McClendon, Ganley is anxiously awaiting further details alongside everyone else.

“What made him do this?” she asked. “If he’s a parent, that’s something I'd like to know. If he has kids, I feel terrible for them.”

Detective Thomas Murphy was the lead investigator on the case in 1988. After he retired, his son joined the force and kept tabs on the investigation’s progress. In a Wednesday press conference, Blodgett thanked the Essex State Police Detective Unit, the Massachusetts Department of Corrections, the FBI, the Tewksbury, Massachusetts PD, the Cullman County Sheriff’s Office, and the Alabama State Bureau of Investigation for their “tireless” work. He also made a special point of calling out Murphy for his assistance, having seen the case through from day one.

“I want to thank everyone involved in this investigation from beginning to end,” Blodgett said. “Their tireless pursuit of justice for Melissa has brought us to this moment. We never forgot about Melissa, nor did we give up on holding her killer accountable.”

McClendon is scheduled to be arraigned Thursday in an Alabama courtroom.