Libby German's grandmother and guardian, Becky Patty, was surprised to learn the man arrested for the murders of Libby and Abby Williams was a Delphi resident.

"It's a small community," she told ABC News hours after Richard Allen's arrest was announced. "For it to be one of us, it's hard."

"How can somebody do that and then just go on living life like nothing happened?" Libby's grandfather, Mike Patty, added.

Libby's sister, Kelsi German, said she always felt the girls' killer must be someone familiar with the Delphi area, but she said she didn't want to believe the suspect "was right here among us."

Mike Patty commended the police officers who he said were diligent and "sacrificed their own family time" to work on his granddaughter's case.

"They never let up," he said.

"There's a lot of questions we have that are unanswered," he added, "but all in due time that will come."

For Libby's sister, the arrest brings "new obstacles and emotions that we have to learn how to deal with."

German said she visited her sister's grave on Sunday to talk to her about the updates in the case.

More than 70,000 tips have been submitted since the murders in 2017, Indiana State Police Superintendent Doug Carter told ABC News.

“The eyes of America were on this” case, Carter said, because Delphi -- a “wonderful community” -- is like so many other American towns.

“We committed a long time ago this day would come,” he said of the arrest.

“Evil never wins,” he added.

As for the girls’ families, Carter said, “I wish I could take their hurt away, but I can’t.”

Carter would not talk about the suspect, Richard Allen, or what led police to him.

The man charged with the girls' murders, Richard Allen, had his initial hearing and entered a not guilty plea, Carroll County Prosecutor Nicholas McLeland said.

Allen was taken into custody on Oct. 26 and is being held at the White County Jail, officials said.

He's being held without bond and is set to return to court in January, McLeland said.

"Per the court order, we cannot talk about the evidence that's in the probable cause" affidavit, McLeland said.

The prosecutor would not say when Allen became a suspect or if he knew Abby or Libby.

McLeland said it's "concerning" to him that Allen is a local Delphi resident. He called the arrest a "step in the right direction."

In the wake of the arrest, Indiana State Police Superintendent Doug Carter said, "Peace came over me -- and I didn’t expect that to happen.”

He said in a message to the families that he hopes they “have found some peace in this complicated world.”

Carter urged the public to “please continue offering tips,” as the investigation is ongoing.

A Delphi, Indiana, man, Richard Allen, has been arrested for the 2017 murders of eighth graders Abby Williams, 13, and Libby German, 14, Indiana State Police Superintendent Doug Carter announced at a news conference Monday.

The 50-year-old was arrested Friday and has been charged with two counts of murder, Carter said.

If anyone else was involved, that person will be held accountable, Carter vowed.

Carter said "today is not a day to celebrate," but called the arrest a "major step."

"This investigation is far from complete," Carter said.

The probable cause affidavit has been sealed, Carter said.

"The time will come when additional details can be released," Carter added.