"Everything we see so far, this appears to be a suicide," Houston said.
Mayfield had faced a conspiracy charge, a felony punishable by up to five years in prison and a $5,000 fine for a conviction. Three other men also were arrested last month and face various charges of conspiring to photograph Rose Cochran in the nursing home where she has lived since 2001 with dementia. The Cochran family said she has lost the ability to speak and is receiving hospice care.
Police said conservative blogger Clayton Thomas Kelly of Pearl photographed the 72-year-old without permission on Easter Sunday. The photos were later used in an anti-Cochran political video posted briefly online during the Republican primary.
All four of the men charged were supporters of state Sen. Chris McDaniel, who lost Tuesday's Republican runoff. Mayfield was a board member of the Central Mississippi Tea Party and had raised money for McDaniel's campaign. McDaniel denies any connection to the scheme.
Janis Lane, president of the board of the Central Mississippi Tea Party, said she had not seen Mayfield since he was charged, but had been in contact with him by phone and through text messages. She said Mayfield's integrity was important to him, and he sounded like he was feeling pressured by the investigation.
"It was truly a challenging time for him," Lane said, wiping away tears.
In a statement, Mississippi Gov. Phil Bryant expressed sympathy to the Mayfield family.
"Deborah and I are saddened to hear of the loss of Mark Mayfield. He was a long-time friend, and he will be missed. Our prayers go out to his family in this tragic moment," wrote Bryant, a Republican.
The Cochran campaign also reacted.
"Obviously, this is a tragic and very sad situation. Mark was a good guy. The senator and all of our thoughts and prayers go out to his family and friends," said Austin Barbour, a strategist and spokesman for the campaign.
Other suspects in the photo plot are elementary school teacher Richard Sager of Laurel and John Mary of Hattiesburg, who took over hosting a conservative talk radio show formerly hosted by McDaniel. McDaniel left the radio job before his election to the Mississippi Senate in 2007.
Lane spoke Friday at the Hinds County Courthouse, where she and other McDaniel supporters were examining poll books to look for examples of crossover voting — people who had voted in the June 3 Democratic primary and in Tuesday's Republican runoff between McDaniel and Cochran.
"He was the finest man," Lane said. "He was an attorney of impeccable character."
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