While he was still a chartered professional engineer and an international professional engineer, his resignation from IPENZ meant the organisation was no longer able to investigate any professional work undertaken by Dr Reay before he registered as a chartered professional engineer in 2011, Dr Cleland said.
"After taking legal advice, IPENZ concluded the investigations could no longer proceed. The complainants have been informed of this," he said.
In response to the IPENZ announcement, Dr Reay issued a statement saying his resignation from IPENZ had nothing to do with its investigation into him.
"Prior to my resignation I was fully committed to the investigations and co-operating with IPENZ in all respects. I expected to see the processes through to a conclusion," he said.
The deaths of those who perished in the quake, which claimed 185 lives in total, and the impact on families was something he thought about everyday, Dr Reay said.
"I was, and am, confident that my conduct at all time complied with my professional obligations, both as a member of IPENZ and as a chartered professional engineer.
"I have willingly taken part in the Royal Commission hearing to help understand why the CTV building collapsed and the investigative processes.
"By February, I had come to have a complete lack of faith and trust in IPENZ generally. I did not act out of what might happen in the future," he said.
Dr Reay outlined a number of concerns he had about IPENZ and claimed the organisation had been "ineffectual in dealing with real issues that affect public safety since the earthquakes".
He also said IPENZ had "responded negatively" to his requests to engage with complainants, and had failed to pass on his request to meet with those who had made the complaint against him.
"The result of these and other concerns was that I no longer had confidence in my professional body and I tendered my resignation."
Police announced in February that engineering firm Beca had been engaged to review information on the collapse of the CTV Building to see whether any criminal investigations should be undertaken.
Police said today the review was ongoing and they hoped to make a decision whether to proceed with criminal investigations later in the year.
Dr Cleland rejected the claims made by Dr Reay.
"We believe we have a good quality process designed for having complaints and we believe we've applied that diligently and professionally," he said.
