The 22-year-old man accused of killing a New Iberia orthodontist in December pleaded guilty to second-degree murder Tuesday.

The plea means Ismael Viera now faces a mandatory life sentence in the Dec. 13 death of Robert Chastant, 59.

Viera’s attorney, Nancy Dunning, a public defender for the 16th Judicial District, admitted her client’s decision was “unusual.”

His plea came after lengthy discussions and a thorough review of the evidence against him, Dunning said.

Ultimately, “he simply didn’t want to go through a trial.”

“He did admit that he hit Dr. Chastant multiple times with a hammer after they had an argument over some tools that belonged to Dr. Chastant,” Dunning said.

Dunning said Chastant hired her client to tend to his horses and to work as a handyman restoring rent houses.

Chastant raised Peruvian horses and owned a horse stable on Sugarmill Road.

At the time of Viera’s arrest, U.S. Immigration and Customs Enforcement placed an immigration hold on Viera.

It is unclear how long Viera had been in the country.

Dunning said the two men became involved in an argument over tools that Viera had used but failed to put back where they belonged. At some point, Viera picked up a hammer and struck Chastant, she said.

“It was really just a very tragic event,” Dunning said.

District Attorney Phil Haney said Chastant died from blunt force trauma to the head.

Because there were no other witnesses to the incident, the defendant’s version of events is the only one available, Haney said.

“We’ll never know if it’s accurate,” Haney said

Viera came to New Iberia from the Lake Charles area, where he had been working with race horses. Chastant had hired him about two months before the killing, Dunning said.

Authorities said Viera and his girlfriend were living in a rent home behind Chastant’s home on Bayou Bend Road in New Iberia.

Dunning said she spent about 10 hours with her client, who was always in the presence of a translator. She said Viera spoke little English.

Haney said Viera will be sentenced July 15. He said the victim’s family members will be given an opportunity to speak during the sentencing.

Haney said he was happy for the victim’s family members that Viera “stepped forward and admitted his guilt.”