Law enforcement said Monday that an arrest had been made in the deaths of Indiana teenagers Abigail Williams and Liberty German, whose 2017 disappearance and murders shocked the nation. 

Indiana State Police announced that Richard Allen, 50, had been charged with two counts of murder related to the girls’ deaths. He has pleaded not guilty. 

Allen’s arrest marks a significant milestone in the nearly six-year investigation into the crime. On Feb. 13, 2017, Williams, 13, and German, 14, went for a hike in the woods in rural Delphi, Indiana, on a day off from school. They were never seen alive again, and their bodies were soon discovered following an extensive search. 

The case generated significant media attention across the country, both for the heinous crime itself and for the fact that social media played a large part in the case. Williams had posted a picture of her and German on Snapchat soon before they were killed, and officials also released a grainy image and audio recording of the alleged killer speaking to the girls. 

During a press conference, Indiana State Police Superintendent Doug Carter called Allen’s arrest “a major step in leading to the conclusion of this long-term and complex investigation,” but added, “This investigation is far from complete.”

Cynthia Rossi, a friend of Williams and German, told CNN there was “a lot of hopefulness” that the arrest would provide closure. 

“I’m glad that justice will be served, hopefully, that that’s what the news is,” Rossi added.