NIWOT, Colo. -- A woman charged with animal cruelty is now accused of hiding 27 horses from the Boulder County authorities.

Marcy Trescott-Helmick, 57, was cited in March after animal-control officers found horses standing in stalls filled a foot deep with feces and urine at the woman's boarding facility in Niwot.

The Boulder County Sheriff's Office called the conditions at the boarding facility "deplorable."

Deputies said they discovered 27 horses were missing during a routine welfare check on the horses at her boarding facility late last week.

"When we went out to do a welfare check on 34 horses, we discovered 27 had been moved. And we don't know where she moved them," said Sgt. Mike Dimond with the Boulder County sheriff's department.

"They can't be monitored, so she is charged with tampering with physical evidence. That's a Class 6 felony," Dimond added.

Seven other undernourished horses were impounded from the woman last month. They are being rehabilitated at Colorado Horse Rescue in Longmont.

"They've all had their teeth checked and they've had some dental work, so they can eat properly and gain weight faster," said Colorado Horse Rescue barn manager Jenny Logan.

"We've seen good improvement on all of them. Several of them have gained up to 70 pounds in just the last month," said Logan.

Trescott-Helmick is now facing tampering with evidence charges. She posted bond on Saturday.

The recent charges are in addition to the nine counts of animal cruelty and 34 counts of improper care for animals she was charged with in March.

Trescott-Helmick had no comment Monday.