UPDATED: 02/04/17, 11:03PM

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ALPINE (CBSDFW.COM) – The investigation continues into the boyfriend of a missing Keller woman police now say they believe they have found in a shallow West Texas grave.

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The remains found Friday are expected to arrive in Dallas sometime Sunday for the medical examiner to identify. However police in Alpine say key evidence found at the burial site leads them to believe this is 22-year-old Zuzu Verk, and they are moving quickly to find out how she got there.

Investigators say since Zuzu Verk went missing in October, they have always kept a close eye on her boyfriend, 26-year-old Robert Fabian. A day after remains were found in a shallow grave just a few miles from his Alpine home, officers arrested Fabian for tampering with or fabricating physical evidence by concealing a human corpse.

Fabian’s sister Jocelin Carrillo told CBS7 in Odessa that her family can’t understand why her brother is behind bars.

“The only question that keeps going through my mind is if the body hasn’t been identified, why was he arrested ’cause the body has not been identified. We don’t know who that body belongs to,” Carrillo said.

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Investigators said a Dallas medical examiner will have to confirm that the remains are those of Verk, but they insist they have no other missing persons, and evidence found at the scene was clear.

“We had evidence to begin with. We recovered more evidence at this scene, and so we felt the time was right to make that arrest,” Alpine Police Chief Russell Scown said.

After the arrest investigators executed a search warrant at Fabian’s family home looking for shovels and other tools, but his relatives insist they’re looking in the wrong place.

“And that’s the scary part. Everybody’s focusing on my brother when somebody’s out there probably sitting around saying, I got away with this,” Carrillo said.

The Brewster County sheriff said dental records may allow them to have a positive identification sometime next week.

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