Massive police search at prison guard David Benbow's house linked to missing Michael McGrath probe

A thorough scene examination of a property linked to the police probe into the disappearance of Christchurch builder Michael McGrath continues today.

Police have now been seen digging at a property linked to the disappearance of Christchurch builder Michael McGrath.

Police say they hope to find McGrath, 49, alive. He was last seen at his Checketts Ave home in the suburb of Halswell on May 21 and reported missing two days later.

Yesterday police searched a property belonging to Christchurch Men's Prison Corrections officer David Benbow, who they say is "a person of interest who needs to be eliminated from the inquiry".

Christchurch Men's Prison Corrections officer David Benbow is a person of interest in the police investigation into missing Christchurch builder Michael McGrath. Photo / via Facebook

Armed police patrolled the cordon around the Benbow property yesterday.

A large blue police tent, initially erected on the road at the entrance to the property, has since been moved inside the gates and white-suited forensic experts are combing the area.

Today, officers have been seen using shovels, dogs and other search tools at the property.

Benbow is listed as owning the property, on the corner of Candys Rd and Sabys Rd just outside Halswell, with Joanna Green.

It's understood that the pair have separated and he has been living at a relative's nearby home.

Police have also been looking at a house owned by Benbow's mother Shirley in the quiet Halswell cul-de-sac of Viceroy Place.

Christchurch builder Michael Craig McGrath, 49, was last seen on Sunday evening May 21 at his home in Halswell, Christchurch. Photo / NZ Police

Police have also been looking at two cars.

Police will hold a press conference to update their investigation at 3pm. A member of the McGrath family will also be at the press conference.

Officers started knocking on McGrath's neighbours' doors last Thursday and finishing examining his red-brick house.

Detective Inspector Darryl Sweeney said police continue to have concerns for McGrath's welfare.

Police inquiries, which include speaking with his family and friends and the scene examination of his home, indicate his absence was completely out of character.

Corrections have referred all enquiries to police.

Sweeney still wants to hear from anyone who had seen McGrath's blue 1994 Subaru station wagon in Christchurch over the weekend of May 21-23, or seen McGrath during that time. He'd also like to talk to anyone he had completed building work for during that time.

McGrath's brother Simon McGrath says although there will "obviously going to be all sorts of theories" about the disappearance, the family is focusing on any sightings of him or his car.

In a Facebook plea for information, Simon McGrath said: "Very unlike him to go walking - has never done so before and he has been in good spirits."

He also wrote that the family was "up and down". "At this stage, all we can mainly do is hope."

Simon McGrath referred other enquiries to police.

Missing person posters have been placed around the area.

One neighbour said police came to her last Thursday wanting to eliminate her silver car from their inquiries.

"It's really strange. It has us all worried," she said.

McGrath's blue station wagon was taken away from his property - just a few doors down from where "Black Widow" Helen Milner fatally poisoned Phil Nisbet in May 2009 - at the weekend.

Neighbours have described McGrath as a quiet man who rarely had visitors.

"We hardly see him," one neighbour said.

"My kids say 'hi' to him when he's out gardening and when he was out biking, which he did a lot."

She said everyone was "really worried", especially at the mounting police activity.

A local shopkeeper said McGrath came in occasionally - but again said he was a very quiet, solitary figure.

She also had concerns for his welfare.

"It's just fingers crossed really," she said.

Anyone who has information about McGrath or has employed him in the past few weeks is asked to call Christchurch police on (03) 363 7400 and cite file number 170523/6008.

Information can also be provided anonymously by calling Crimestoppers on 0800 555 111.