Pennsylvania police's 34-year search for answers about Tracy Kroh's whereabouts continued this week with a "methodical demolition" of the main suspect's home.

Kroh was 17 when she was last seen at the Alex Acres Mobile Home Park in Halifax, Pennsylvania, around 10 p.m. on Aug. 5, 1989.

Police believe she was kidnapped and murdered, but her body was never found, and no one was charged with her disappearance.

The main suspect, Mark Warfel, who is now 90 years old and reportedly suffers from dementia, is the biological father of Kroh's younger sister.

This week, Pennsylvania State Police are tearing down all the buildings on Warfel's Mountain House Road property in Jackson Township, which is about 10 miles from where Kroh was last seen alive.

State Police said in a statement that Warfel's family is cooperating and consented to the operation.

"The Pennsylvania State Police remains unwavering in its commitment to bring this investigation to a conclusion and provide closure for the Kroh Family," they said. 

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The "methodical demolition" of all structures on the property is a "means to further the investigation," according to police. 

However, a police spokesperson did not answer questions about why they are razing the property or what they are looking for.

Warfel is in jail for unrelated charges of assaulting a hospital nurse, which were filed less than a month after a judge ruled that he was not fit to stand trial for a 2019 incident when he allegedly broke into a woman's home.

Shortly after his 2019 arrest, law enforcement searched his property for the first time in connection with Kroh's case. 

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Police said Warfel was a suspect in Kroh's death, as well as his wife's death, during his competency hearing in 2022. 

Kroh was reportedly visiting Kroh's sister the night she went missing and never returned to her Millersburg home, which is less than 10 miles away, according to the FBI's missing person profile.

The next day, investigators found her car in Millersburg town square, but none of her belongings were inside.

In December 1993, parts of her wallet were discovered along the Wiconisco Creek in Washington Township, which is about nine miles from Millersburg, according to the FBI. 

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Over the last three-plus decades, only two other names have been publicly connected to Kroh's case. 

Those were Holly Mallett and Matthew Webster, who were both charged with perjury for lying to a grand jury in connection with Kroh's case. 

Webster told Mallett, "It was supposed to be just a rape and done, but then it turned out to be a lot more," according to a probable cause affidavit.

A court-authorized wiretap caught Webster telling Mallett what to say to the grand jury. 

Both were arrested and charged with perjury. Mallett pleaded guilty, and Webster pleaded no contest. 

Despite the charges, authorities have not publicly named either as suspects in Kroh's presumed murder.