Sources: Middleman in contact with assailants at time of Tokyo couple's murder

Japanese investigative sources say a man arrested over the killing of a married couple has said he was in contact with two other suspects by cell phone when the victims are believed to have been killed.

Tokyo police on Saturday served a fresh arrest warrant on Hirayama Ryoken for allegedly killing Takarajima Ryutaro and his wife, Sachiko. Their bodies were found in Nasu Town, north of Tokyo, in mid-April.

Hirayama had initially been arrested on suspicion of damaging the victims' corpses by setting them on fire.

Police say Hirayama served as a middleman between two assailants and a man who issued instructions for the couple's murder and disposal of their bodies.

They also suspect he conspired with other suspects to strangle and beat the couple in a vacant house to kill.

Investigators say security camera footage captured Hirayama near the house when the victims are believed to have been killed.

Investigative sources say he told police that he stayed close to the house until the assailants drove out of it.

Police believe Hirayama was contacted by the assailants when they headed for Nasu and knew what was happening in detail.

Police are trying to determine how each suspect was involved in the case.