A manhunt for a Rexford woman accused of murdering her 3-year-old niece and threatening the child’s family members is over after her arrest Monday morning in Missoula County.

Tina Marie Mergenthaler, 57, is charged in Lincoln County with one felony count of deliberate homicide, one felony count of witness tampering and one felony count of evidence tampering.

She is scheduled for an initial appearance at 2:30 p.m. today in Missoula County Justice Court.

An arrest warrant for Mergenthaler was issued Friday, Nov. 6, by Lincoln County Justice of the Peace Jay Sheffield. He also found probable cause for the case to proceed following the filing of charges by county attorney Marcia Boris.

The warrant was entered into the teletype system in Montana, Idaho, Washington and Oregon. The system allows various law enforcement agencies to rapidly communicate across jurisdictions regarding felony warrants or BOLO (Be on the Lookout) alerts. When an officer makes a traffic stop or arrest and a database match (hit) occurs, a teletype notification is sent to the arresting and warrant-holding agencies.

Judge Sheffield ordered Mergenthaler held without bond.

While details of her arrest by the U.S. Marshals Service were not immediately available, Missoula County Jail Roster records indicated the fugitive was booked into the facility at 10:48 a.m.

Court officials said Mergenthaler is scheduled to make her initial appearance in Missoula County Justice Court at 2:30 p.m. Tuesday.

Investigators from the Lincoln County Sheriff’s Office, including the since deceased deputy Ryan Terpsma, Montana State Crime Lab, Flathead County Sheriff’s Office and Montana Department of Justice’s Division of Criminal Investigation (DCI) worked together in painstaking fashion to assemble the case, that spanned three months, along with help from Oregon officials.

Charging documents paint a disturbing picture of chronic abuse and neglect, alleged threats to the deceased girl’s brothers, an attempted cleanup of the crime scene and multiple attempts to deceive law enforcement officers investigating the alleged offense.

After the lengthy investigation, recent developments opened the door for charges to be filed.

On Monday, Nov. 2, DCI agents Cynthia Lengyel and Alesha Woodland met with one of the brothers at the Oregon Department of Human Services Child Care Center in Klamath Falls.

The 5-year-old child didn’t want to talk about his time in Montana, but he did ask where his aunt, Mergenthaler, was. He did express his worry and the difficulty in speaking about what happened in Montana. 

The child also said he told his foster mother what happened. The agents then spoke to the woman and learned the 5-year-old was in her care since Aug. 11.

The woman told investigators after she returned home from a recent trip to a correctional facility to visit another child in her care, the boy asked her if his aunt was going to be arrested. The woman said she wasn’t aware of it.

A few moments later, the child returned to his foster mother and said, “She really needs to be arrested.” The woman asked why and he said, “because she killed my sister.”

Law enforcement received evidence results Nov. 3 from the Montana State Crime Lab that opened the door to charges being filed. Evidence analysis typically takes months due to the volume submitted to the lab.

DCI Agent Cynthia Lengyel received a report that indicated a piece of wood trim seized during a Sept. 3 warrant search contained blood, hair and fibers. The charging document also said a DNA report from the crime lab was forthcoming.

According to the affidavit, law enforcement wasn’t able to contact Mergenthaler since Aug. 11, three days after the alleged crime. They reported she abandoned all of her property at a Pinkham Creek area residence. Also, no family members or church members had seen her since Aug. 11.

Aug. 10, county detectives Dan Holskey and Brandon Holzer, along with county coroner Craig Riddle, attended the deceased child’s exam in Missoula. The medical examiner (ME) was confident the girls’ injuries were not due to a fall. The ME also reported seeing a tread imprint on the toddler’s head and he determined the manner of death to be homicide.

On Sept. 1, the detectives went to the Pinkham Road property following a request by the landowner. The saw towels that appeared to have bleach stains. Two days later, officers returned with an evidence collection team from Flathead County. Trace evidence not visible to the naked eye was seen after a chemical was applied that illuminates when in contact with human blood.

Oct. 16, DCI Agent Lengyel and county Det. Dan Holskey met with state Crime Lab medical examiner, Dr. Civan Altunkaynak. He reported extensive brain bleeding, a broken upper jaw, external healing kidney scars that were multiple weeks old and several rib fractures at different stages of healing.

The investigation began at about 12:42 p.m. Saturday, Aug. 8 when county deputies Scott Welchons and Terpsman responded to a Pinkham Road residence in Rexford after a 911 call indicated a juvenile female had fallen from a tree.

Deputy Terpsma found the accused performing chest compressions on the toddler. She was on the sink counter in the bathroom with only her underwear on. When he and Welchons took over CPR, Mergenthaler allegedly said the girl, “must have hit her head or something…she was knocked out and not breathing so I came in, out her here and started breathing for her…you want to take over, my arms are really tired.”

Investigators noted Merganthaler wore a black T-shirt, light-colored blue jeans and appeared to have wet hair. 

The little girl’s brothers, age 5 and age 12, were in the home at the time.

On the day the child died, her older brother said his sister fell out of an apple tree when Deputy Terpsma asked him what happened. Mergenthaler allegedly interjected, “you told me the next thing you know is she fell.”

A conviction for deliberate homicide is punishable by life, death or a state prison term for a minimum of 10 years or more than life.

Convictions on each of the tampering charges are punishable by a maximum term of 10 years in state prison as well as fines up to $60,000.