JEFFERSON CITY, Mo. -- The spokesman for the Missouri auditor's office left a note before he was found dead of an apparent self-inflicted gunshot wound late Sunday, about a month after his boss killed himself, police said Monday.

Robert "Spence" Jackson was found dead in his home in Jefferson City after police responded to a well-being check, police spokesman Capt. Doug Shoemaker said. He said investigators found a note in Jackson's apartment, but he declined to detail what it said.

Jackson's boss, Auditor Tom Schweich, fatally shot himself at his home on Feb. 26, shortly after telling an Associated Press reporter he wanted to go public with allegations that the Missouri Republican Party chairman told people he was Jewish. Schweich, who was Christian, said he perceived the remarks to be part of an anti-Semitic whispering campaign against him.

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Jackson was among the first to suggest after Schweich's funeral that the chairman, John Hancock, should resign. Hancock has denied making anti-Semitic remarks and remains the party's chairman.

Shoemaker said police were well aware of the political issues surrounding the deaths, but that investigators wouldn't comment "or really entertain questions that might link Mr. Jackson to any type of political issue, whether it's perceived or real."

Shoemaker said investigators believe Jackson, 44, shot himself either Friday night or early Saturday, and that authorities found a gun near his body. He said Jackson's mother called police Sunday after being unable to reach him.

Missouri Gov. Matt Blunt, for whom Jackson also had previously worked, issued a statement Monday saying he was saddened to learn of his friend's death.

"Spence was a gifted communicator who dedicated his talents in public affairs to public service," Blunt said. "Spence was hard-working, well-liked and quick-witted."

Jackson had remained as the auditor's office spokesman after Schweich's death.

Police said they responded to a call to Jackson's apartment a little after 7 p.m. A property manager provided a key to police officers, who found Jackson dead in his bedroom from an apparent self-inflicted gunshot wound, according to police. Police said there was no physical evidence of a forced entry or struggle, but that an autopsy is planned for Monday and detectives are continuing to investigate the case.

Schweich's death roiled the Missouri Republican Party as it prepares for the 2016 election featuring races for U.S. Senate, governor and most of Missouri's other statewide executive offices.

Hancock has remained on the job. He has denied making anti-Semitic remarks, though he has said it's possible he might have told some people that Schweich was Jewish because he mistakenly believed that to be true.

CBS affiliate KMOV reports that Jackson was Schweich's media director for four years and he also held several key Republican jobs in state government.

Jackson had worked in various Missouri government and political jobs over the past 15 years. He served as Blunt's spokesman in his successful 2000 campaign for secretary of state and then joined Blunt's official staff. Jackson also served as Blunt's campaign spokesman in his successful 2004 gubernatorial bid and again rejoined his office.

Blunt moved Jackson to the state Department of Economic Development in 2006. When Blunt chose not to seek re-election, Jackson served as campaign spokesman for Sarah Steelman's unsuccessful 2008 gubernatorial bid. He joined Schweich's staff at the auditor's office in October 2011.