Pennsylvania authorities conducted a nine-year investigation before arresting a man in the murder of his wife.

The investigation began after Olga Sanchez, 30, burned to death in a house fire in Lancaster in 2010, police said. The fire was ruled arson after investigators determined it was started with gasoline.

On Thursday, Carlos Montalvo-Rivera, 52, was charged with arson and murder in the death of his wife, police said. He was also charged with trying to kill their young children, ages 13, 9 and 8, each of whom survived the fire.

Montalvo-Rivera was being held without bail.

“Every time we reviewed this case, every time we looked at the evidence, the finger of guilt pointed back at one person,” Lancaster County District Attorney Craig Stedman said, according to Fox 43 York.

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Montalvo-River told police he and his wife were happily married and denied having any marital problems, the station reported.

But Sanchez’s sister Dolores Ojeda told detectives the marriage was on the rocks.

“I will kill you like a dog,” she quoted Montalvo-River as telling her sister a year before she was killed, according to the station.

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Police said Montalvo-Rivera’s account of what happened was riddled with inconsistencies, beginning with his claim that intruders set the fire after breaking into the house and knocking him unconscious for 45 minutes.

A neurologist told investigators last month that based on medical records, Montalvo-Rivera’s version of what happened was “highly unlikely.”

“The medical science is not backing up what the defendant is claiming that he had been knocked out for 45 minutes, which is an excessively long time for a significant head injury," Stedman said, according to the station.

A neighbor also refuted Montalvo-Rivera’s account that he escaped the fire with his hands tied behind his back.

The neighbor said that after he reported the fire, he saw Montalvo-Rivera with his hands untied trying to climb into a second-floor window and then tried unsuccessfully to help him.

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