Indiana State Police announced Monday the arrest of Richard Allen in connection to the killings of two teenage girls nearly six years after the best friends were found dead on a hiking trail.

The lifeless bodies of Liberty "Libby" German, 14, and Abigail "Abby" Williams, 13, were found Feb. 14, 2017, one day after German's sister dropped the two friends off at the entrance to a hiking trail in Delphi – a city northwest of Indianapolis.

"Today is not a day to celebrate," said State Police Superintendent Doug Carter at a press conference at Delphi Methodist Church. "The time will come when additional details can be released but today is not that time."

Allen, 50, was taken into custody Friday and booked in the Carroll County Jail on two counts of murder, he said.

DELPHI MURDERS: INDIANA MAN REPORTEDLY IN CUSTODY IN CONNECTION WITH 2017 KILLINGS OF 2 GIRLS

Richard Allen booking photo

Authorities announced Monday, Oct. 31, 2022, the arrest of Richard Allen, center, in connection to the murders of Libby German, left, and her best friend, Abby Williams, in February 2017. (Indiana State Police)

Allen worked at a local CVS, and his home was searched last week, with investigators focusing on a fire pit, according to FOX 59.

He pleaded not guilty at his initial hearing and was not granted bond, Carroll County Prosecutor Nicholas McLeland said at the press conference.

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German's sister, Kelsi German, wrote in a tweet Monday, "We got him."

Officials offered few new details, and the arrest affidavit and charging documents, which are usually public in criminal cases, were sealed by the court.

"We haven’t closed the door on the investigation," McLeland said. "We’re not presuming anything at this point."

Suspect composites in Delphi case

Two different composite sketches and a grainy image of the murder suspect. (Indiana State Police)

Police previously said the girls were found covered in blood, and the killer had taken a memento from the crime scene. However, police have not disclosed how the girls were murdered or the evidence they have obtained in the case.

Days after the killings, officials released two grainy images of a man walking across an abandoned railroad bridge taken on German's phone shortly before the girls' remains were found in a wooded stretch off the Delphi Historic Trail.

The phone also had an audio recording of a man, believed to be the killer, ordering the pair "down the hill."

Kegan Anthony Kline mugshot

Indiana State Police petitioned Miami County Circuit Court for custody of Kegan Kline, 27, on Aug. 19, 2022. (Miami County Sheriff's Office)

However, the case stymied investigators for more than five years with lead after lead turning cold.

Days after the killings, authorities executed a search warrant on the property of Ron Logan, where the girls' bodies were found.

Logan had lied about his whereabouts the day of the double homicide, according to investigators.  He died in January and was never publicly named a suspect, according to FOX 59.

In August, Indiana State Police petitioned Miami County Circuit Court for custody of Indiana man Kegan Kline, 27, who is locked up on child pornography charges.

Kegan Kline linked to 'anthony_shots' Instagram

Kegan Kline was allegedly behind the fictitious Instagram account "anthony_shots" that he used to communicate with underage girls – including Liberty German the day before she turned up dead on a hiking trail. (Indiana State Police)

Kline had been in contact with German using the fake Instagram account "anthony_shots" the night before she was murdered, according to FOX 59.

He allegedly made plans to meet up with her around the time she went missing, but Kline has denied any involvement.

The "Murder Sheet" podcast obtained a 2020 transcript of a police interview with Kline, who admitted he was in touch with the girl.

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The transcript also revealed that Kline searched "How long does DNA last" on his computer and failed a police polygraph test.

Police have not said whether they believe Logan or Kline are involved in the murders.

Haley Chi-Sing contributed to this report.