A medium who named two people she claims murdered Scott Guy has been accused of "exploitainment".

During a show at the Regent Theatre in Palmerston North last month, British clairvoyant Lisa Williams gave the names of two men she claimed shot the dairy farmer.

Police said they were aware of the names and were checking them against their suspect list.

Williams claimed to be "channelling" Guy - speaking to him from beyond the grave - and was told his killers' first names were Mark and Joey. A cousin of Guy's who was in the audience became upset and started crying during the show, said one audience member.

Guy's sister Nikki said she was aware of Williams' claims.

She said: "My first reaction was hope, and then I thought about it for a few days and it almost becomes despair.

"If something comes out of it, that would be fantastic, but I am not holding out much hope."

Williams, who lives in Los Angeles, was accused of exploiting the "most vulnerable members of society" by the Sceptics Society.

Spokeswoman Vicki Hyde said: "It's exploitainment. No psychic has ever produced any substantive information that wasn't already known or been blindingly obvious.

"The psychic industry relies on psychological manipulation."

Williams, who claims she has been able to speak to dead people since she was a child, did not respond to interview requests.

Fan Lynn Cachemaille, who attended the Palmerston North show, said it was like watching an episode of Sensing Murder.

"It was quite scary. She said [Scott Guy's killers] came from over the sea and had since left the area." A Trade Me user who attended the show said: "What absolutely blew everyone off their seats was when the energy of Scott Guy came through, and you could've heard a penny drop, she knew specifics that nobody would've ever known, not even the police."

Williams described some circumstances of the killing last July 8 that had been widely reported. She also claimed a white or grey sedan was used by the killers to flee the scene.

Detective Inspector Sue Schwalger said the investigation team was aware of Williams' claims.

She said: "Any information the team receives in respect of Scott Guy's murder, irrespective of where it comes from, will be looked at, evaluated and assessed against the information we currently have."

One senior private investigator said police could not afford to dismiss information from psychics - especially in complex "whodunnit" investigations.

Ron McQuilter, managing director of Paragon Investigations, said: "With psychics, you are damned if you do and damned if you don't. You can't ignore it in case it turns out to be significant. If that means a psychic, then that means a psychic."

He also said he believed the investigation would benefit from bringing private investigators in.

"I have nothing but praise for the police, but I think a fresh set of eyes could help."

Schwalger said last week she believed police had already interviewed Guy's killer.

His widow Kylee also made a fresh appeal for anyone with information about Guy's killing to come forward.