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An Indiana man is reportedly in custody in connection with the Delphi murders of two young girls in 2017.

Liberty "Libby" German, 14, and Abigail Williams, 13, were found murdered on the afternoon of Feb. 14, 2017, after German's sister dropped the pair off at the entrance of a hiking trail the day prior.

Now, sources are telling FOX 59 Indianapolis that a man named Richard Allen, 50, is in custody in connection with the murders.

"Just know how grateful I am for all of you," Liberty German's sister, Kelsi German, said in a Friday afternoon tweet. "No comments for now, any questions please refer to the Carroll county prosecutors office. There is tentatively a press conference Monday at 10am. We will say more then. Today is the day."

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Delphi, Indiana murders Libby German and Abby Williams

On Feb. 14, 2017, Libby German, 14, and Abby Williams, 13, were killed while biking on trails near Delphi, about 60 miles northwest of Indianapolis. (Indiana State Police)

She added that "nothing is confirmed at this time."

Police say German used her cell phone to snap images of a man walking across the railroad bridge shortly before she and Williams' bodies were found on Feb. 14 in a wooded area near the Delphi Historic Trail. German also recorded the man believed to be the killer ordering the pair "down the hill."

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Journalist Áine Cain and attorney Kevin Greenlee, who host "The Murder Sheet" podcast, obtained court documents in May and August indicating possible developments in the case involving two different men. 

In May, Cain and Greenlee obtained a search warrant saying authorities searched the property of Ron Logan, near where the girls were found on March 17, 2017. He died in January and was never named as a suspect. 

Suspect composites in Delphi case

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

The killer likely took a souvenir from the crime scene and removed something or took photos to "memorialize the crime scene," according to documents obtained by The Murder Sheet.

The warrant obtained by the podcast hosts also said Logan also lied about his alibi and instructed a family member to lie to police about his whereabouts. 

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Then, on Aug. 19, the ISP petitioned the Miami County Circuit Court for custody of an Indiana man name Kegan Kline, 27. Kline is currently in custody in Miami County for 30 counts of child pornography-related charges dating back to 2016 and 2017.

Kline, who lived near the location where the girls were killed, had been perviously linked to the Delphi murders because he was reportedly in contact with German using a fake social media account the night before she was murdered, according to FOX 59. He allegedly made plans to meet up with her at the bridge where her body was found the next day, but Kline denies that he had anything to do with the girls' killings.

Kegan Kline linked to 'anthony_shots' Instagram

In December 2021, the Indiana State Police said in a Facebook post that they had uncovered a fictitious Instagram account under the username "Anthony_Shots" in their investigation into the Delphi murders.  (Indiana State Police)

In December 2021, ISP said in a Facebook post that they had uncovered a fictitious Instagram account under the username "Anthony_Shots" during their investigation into the murders. 

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In March, Cain and Greenlee obtained a 2020 transcript of an ISP interview with Kline that was accidentally posted online indicating that Kline had access to the account, which had been in contact with German. However, Kline told investigators that he gave the account password to "a lot of people," according to the document.

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According to the transcript, which has since been sealed in the court record, Kline told police he communicated with German on the day she was killed. The transcript also revealed that Kline searched "How long does DNA last" on his computer and failed a police polygraph.

Authorities are asking anyone who may know something about the Instagram profile or anything about the case to contact law enforcement at abbyandlibbytip@cacoshrf.com or 765-822-3535.

Fox News' Louis Casiano contributed to this report.