A disputed drug debt for efforts to produce methamphetamine led to the cold blooded killing of a criminal known as "Granite," Tauranga District Court was told today.

Local company director, Brett Michael Ashby, 50, is appearing at a depositions hearing charged with the murder of Grant Adams, who went missing in December 2005.

The skeletal remains of what is believed to be his body were dug up by police in the grounds of Wairakei geothermal power station near Taupo early in July last year.

"Granite" was allegedly shot several times in the back and once in the head with a semi-automatic pistol.

A further charge against Ashby of manufacturing methamphetamine between January 1, 2005, and June 28, 2007, was withdrawn at the start of the proceedings.

The evidence of more than 50 witnesses will go before Community Magistrate Robyn Paterson, the majority of it in written hand-up statements.

First to take the stand is Craig Cullen, 44, who pleaded guilty last month to being an accessory after the fact of Adams' murder.

He was sentenced to 12 months' home detention in the High Court at Rotorua.

Cullen, who had worked with Adams for Ashby on efforts to manufacture methamphetamine, led police to the grave site and has been granted immunity from prosecution over the murder.

Lawyers Greg Hollister-Jones and Rob Ronayne appear for the Crown and Greg King, assisted by Elizabeth Hall, for Ashby.