John Dalton
John W. Dalton Jr. was a person of interest in the three killings after being released from prison. Omaha Police Department

A convicted killer released from prison was being sought by Nebraska police after a triple homicide Tuesday. John W. Dalton Jr. was a person of interest in the three murders, according to Omaha Police Capt. Thomas Shaffer.

Dalton, 46, previously served 11 years in prison for killing his then 22-year-old wife Shannon Dalton in 1998, the Omaha World Herald reported. After taking a plea bargain that allowed him to avoid a life sentence, he was released from prison in 2010.

Dalton reportedly expressed his regret for killing his wife at the time, according to a letter read at the trial.

“I wish I could go back and change that whole day around,” Dalton wrote, according to the World Herald. “I miss my wife so much.”

The three victims of Tuesday’s killings were identified as Dalton’s father, John W. Dalton, 70, his mother, Jean Dalton, 65, and his niece, Leonna Dalton-Phillip, 18, WOWT-TV reported. All three were killed by gunshot wounds to the head and police said Dalton owned the home where they were killed, according to the World Herald.

Police were alerted to the killings after a girl ran into a neighbor’s home and told them her family had been shot. The neighbor called 911 and officers were deployed to the scene, but Dalton had already fled by the time authorities arrived.

“We are in the early stages of this investigation and have taken some statements,” Shaffer said in a press conference.

Police still had not located Dalton Wednesday afternoon and said he was considered armed and dangerous. Authorities urged the public to look out for a black 2015 GMC Terrain with Nebraska license tags UKB787 or a red 2007 Chevrolet Tahoe with Nebraska license tags VRD559. Anyone with information about Dalton or the killings were asked to call 911.