The body of the 32-year-old father of three was found in the back yard of his property near the small, semi-rural town northwest of Auckland on July 29.
Investigation head Detective Inspector Greg Cramer said 33 police staff were still working on the homicide investigation.
"We're in this inquiry for the long haul. We're crossing every T and dotting every I and making sure that we're being very thorough,'' he said.
Police were still awaiting test results from the abundance of forensic evidence gathered from Mr McMurdo's large, overgrown property.
"Contrary to the image portrayed by CSI, these results do take some time to come back. They could be some time off yet.''
Police would not revealed how Mr McMurdo was killed but have said his death was violent.
He was involved in the drug scene and was facing charges of cultivation of cannabis and possession of cannabis for supply at the time of his death, Mr Cramer said.
Court staff said he had appeared in Waitakere District Court seven times between January and June 2011 but had not been convicted.
Mr Cramer said suggestions his death was drug-related were merely speculation.
Mr McMurdo's parents, Bruce and Sue, last month made a public appeal for information about their son's killing.
Mr Cramer said information from members of the public was still trickling in, but there would still be people out there with information that could be more valuable than they realised.
"The police are looking for any information at all and we are the best judges of whether it's relevant or not.''
There was still no sign of a flat-screen television and a black wallet, containing a cash card and a Video Ezy card with Mr McMurdo's name on it, which were missing from his house, Mr Cramer said.
