Investigators in two states were trying Thursday to find the motive behind the murder-suicide of an Oklahoma "perfect couple" and their baby daughter by the woman's husband. 

Police claim Daniel J. Johnston, 29, of Edmond, Okla., killed his wife and 16-month-old daughter, then flew 1,000 miles to Las Vegas, where he apparently committed suicide in a hotel room.

Johnston was found dead Tuesday night at the Mirage resort hotel, according to Las Vegas Police Officer Laura Meltzer. Authorities have not yet released an official cause of death, but are calling it a suicide.

Johnston was suspected of killing his wife, Tara Shay Johnston, 29, and their daughter Allison Sue Johnston. The two were found dead in the family's home shortly before 8 a.m. Tuesday, though it is not clear when they were killed. 

Investigators in Oklahoma believe Johnston killed his wife and child before flying to Las Vegas on Sunday, according to Fox affiliate KVVU-TV. 

"We thought the marriage was great," Tara Johnston's uncle, Bill Lisby, said in an interview with

"We didn’t see anything wrong ... He took care of Tara and the baby. Allison was his pride and joy. He was really liked within the family," said Lisby, who described Johnston as "really polite" and "clean cut." 

Lisby said the couple had met while working together in a restaurant that Johnston had managed. The two have been married for a few years, he said. 

The man's father, Charles Johnston, reportedly wrote on his Facebook page that his son killed himself by cutting his wrists and ankles. 

Police discovered the bodies of Tara Johnston and her daughter after receiving an anonymous tip that two people were dead inside the family's home near Oklahoma City.  

"It was clearly, clearly, a homicide ... a double homicide," Sgt. Gary Knight told the Associated Press, adding that police believe Johnston killed himself. He said the state medical examiner's office is still working to determine when and how Johnston's wife and daughter died.

"We don't know a motive at this point," Knight said.

A search of state and federal online court records show only a traffic ticket for Daniel Johnston.

 Click for more on this story from's Cristina Corbin and the Associated Press contributed to this report.