State and federal investigators are trying to find out who hung seven nooses in trees outside the Mississippi Capitol early Monday, a day before a U.S. Senate runoff that has focused attention on the state's history of racist violence.

The Mississippi Department of Public Safety says the nooses were accompanied by handwritten signs referring to Tuesday's election as well as to lynchings — most of them in the state's turbulent past, but also one recent case that remains under investigation, of a black man whose body was found hanging in central Mississippi. The department posted photos of the signs on social media and sought information about them from the public.

One sign referred to the Tuesday runoff between appointed Republican Sen. Cindy Hyde-Smith, who is white, and Democrat Mike Espy, who is black. The sign also read: "We need someone who respects the lives of lynch victims."

Another sign read: "We're hanging nooses to remind people that times haven't changed."

Hyde-Smith has drawn fire for a photo showing her wearing a replica hat of a Confederate soldier, and a video showing her praising a supporter by saying, "If he invited me to a public hanging, I'd be on the front row." She said the hanging remark was an "exaggerated expression of regard" for the supporter, but the remarks drew sharp criticism in a state with a 38 percent black population. She apologized "to anyone that was offended."

Espy is trying to become the first African-American U.S. senator from Mississippi since Reconstruction.

At a midday event, before the content of the signs was disclosed, Espy said he knew nothing about the nooses or signs. He said it would be "unfair" to make any connection between the items and Hyde-Smith.

Hyde-Smith campaign spokeswoman Melissa Scallan later condemned the nooses by saying: "Obviously, this behavior is offensive and has no place in a civilized society."

Chuck McIntosh, a spokesman for the Mississippi Department of Finance and Administration, which oversees the Capitol, said the nooses and signs were found starting shortly before 8 a.m. Monday outside the Capitol in downtown Jackson.

The matter is under investigation by the Mississippi Department of Public Safety, Mississippi Capitol Police and the U.S. attorney's office.

"With our law enforcement partners, we are actively looking into these acts of hate and intimidation," U.S. Attorney Mike Hurst said in a statement. "Let me be perfectly clear — there is absolutely no place in our state for these unacceptable symbols or tactics to intimidate others. If we find evidence beyond a reasonable doubt that a federal crime has occurred, these criminals will be swiftly prosecuted."

Republican Lt. Gov. Tate Reeves, who has an office in the Capitol, called the nooses and signs "reprehensible."

Mississippi has a history of racially motivated lynchings. The NAACP website says that between 1882 and 1968, there were 4,743 lynchings in the United States, and that nearly 73 percent of the victims were black. It says Mississippi had 581 lynching during that time, the highest number of any state.

Civil rights activists were also beaten and killed in Mississippi as they pushed for African-Americans' voting rights, particularly from the end of World War II until the 1960s. A Mississippi official says two nooses and six signs were found on the grounds of the Mississippi state Capitol.

Chuck McIntosh, a spokesman for the Mississippi Department of Finance and Administration, which oversees the Capitol, says the nooses and signs were found Monday morning shortly before 8 a.m. on the south side of the Capitol grounds.

He says the matter is under investigation, and he did not immediately know what was on the signs.

A local television station showed photos of the nooses hanging over tree limbs, and described the rest as "hate signs."

Mississippi is preparing for a Tuesday Senate runoff between Republican Sen. Cindy Hyde-Smith and Democrat Mike Espy in a race that has increasingly taken on racial overtones.