Investigators are trying to find out who hung seven nooses in trees outside the Mississippi legislature early on Monday, a day before a US Senate vote that has focused attention on the state’s history of racist violence.

The Mississippi Department of Public Safety said 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 from the public.

One sign referred to the Tuesday run-off between appointed Republican senator 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.”

Cindy Hyde-Smith
Cindy Hyde-Smith (Rogelio V Solis/AP)

Ms 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% black population. She apologised “to anyone that was offended”.

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

Mike Espy
Mike Espy (Rogelio V Solis/AP)

Donald Trump praised Ms Hyde-Smith as he headed to Mississippi to lead two rallies for the senator.

The president said she has apologised and misspoke, adding that her comments were “taken a certain way but she certainly didn’t mean it”.

Neither of the candidates has commented on the nooses.

Chuck McIntosh, a spokesman for the Mississippi Department of Finance and Administration, which oversees the state capitol, said the nooses and signs were found starting shortly before 8am on Monday outside the building in central Jackson.

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

Donald Trump during a rally for Cindy Hyde-Smith
Donald Trump during a rally for Cindy Hyde-Smith (Alex Brandon/AP)

“With our law enforcement partners, we are actively looking into these acts of hate and intimidation,” US 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 lieutenant governor 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 US, and that nearly 73% of the victims were black. Mississippi had 581 during that time, the highest number of any state.

Civil rights activists were also beaten and killed in Mississippi as they pushed for African-American voting rights, particularly from the end of the Second World War until the 1960s.