SEATTLE TIMES FILE PHOTO

Joseph Naimo is accused of poisoning his wife in November 2008.

A mistrial has been declared in the trial of a Federal Way man charged with first-degree murder in connection with his wife's 2008 death. On Wednesday, after more than a week of deliberations, the jury announced it could not reach a verdict.

The jury was split 9-3 in favor of convicting Naimo, said Dan Donohoe, spokesman for the King County Prosecutor's Office.

Joseph Naimo was being tried for first-degree murder in connection with the death of Ann Naimo, his wife of 10 years. Authorities say that Ann Naimo died after a massive dose of strychnine, a chemical commonly found in professional-grade rodent bait, was found in her system. Joseph Naimo was the general manager of AA Pest Control in Kent.

During the trial, Deputy Prosecutor Jimmy Hung said Naimo killed his wife because he was tired of her nagging "and had his eyes on another woman," according to the Tacoma News Tribune.

But defense attorney Les Tolzin said Ann Naimo intentionally ingested the strychnine, the News Tribune reported. Tolzin argued the prosecution couldn't rule out suicide and, as a result, didn't prove beyond a reasonable doubt that Naimo killed his wife.

According to police, Naimo called 911 on Nov. 28, 2008, to report that his wife wasn't breathing. He told police that the couple had been fighting that day because she had been drinking. Naimo told investigators that they were recovering alcoholics, court charging papers said.

Naimo told investigators that after the argument, his wife walked to the back bedroom and began vomiting. He said that after about two minutes he found her lying on the futon; her eyes were open but she was not breathing, charging documents said.

An autopsy initially found nothing suspicious, police said. But several months later the King County Medical Examiner's Office alerted them that blood tests had come back showing lethal levels of strychnine in the woman's blood.