After spending the first five days after the quake in charge of body removal from sites in the city to the morgue at Burnham, experienced search-and-rescue man Brian Benn, a senior sergeant with the Dunedin police, volunteered to oversee the search operation inside the central city cordon area.
He was in charge of the massive central city search operation from February 26, five days after the earthquake, until the rescue mission was officially moved to a recovery mission last Friday.
Working from four fire-service command units at agency command HQ in Latimer Square, Snr Sgt Benn's job was to ensure every building and rubble pile within the 113-block cordon was clear of people, alive or dead, before the cordoned area could be reduced.
The task involved co-ordinating 35 search teams working within the cordon during the day, and 15 teams working through the night, as well as police officers working with each search team, police victim-recovery dog teams, engineers, locksmiths, SPCA staff and others assisting with the search effort.
Back in Dunedin this week, Snr Sgt Benn said the job largely involved organising, delegating and troubleshooting to ensure teams' access to properties was smooth, and they had everything they required to search safely and properly.
Searchers meant all those in all teams, from the "heavy" search teams of national and international urban search-and-rescue (USAR) organisations, to "light" search teams from agencies such as the Red Cross.
Information from each team was entered into a spreadsheet, which was transferred on to a GIS (geographic information system) map of the area, which showed which buildings had been searched.
The work was made more difficult by the rubble, which could not be attributed to certain addresses for recording, and continuing aftershocks, which often resulted in new piles of rubble that then needed to be checked.
Having joined the search effort after initial searches were done, his task was to manage the undertaking and completion of the search to a standard where he was confident the cordoned area was clear and could at least be reduced, so some people could get back into their businesses and homes.
The search was a detailed and complex process, managed by dividing the work into "bite-sized chunks", Snr Sgt Benn said.
After buildings were stickered green, yellow or red, teams would enter them, with an engineer if they saw a safety risk.
They would check each property visually, physically, and then with one of nine police victim-recovery dogs, which can detect a body up to a metre underneath debris.
Buildings were searched up to three times, before being marked off, on the building and on the map, as clear.
Dealing with piles of rubble was more difficult, because they did not have addresses, and the marking of them and recording of whether they had been searched became an issue.
Each pile of rubble had to be visually checked, physically checked, then have a victim-recovery dog go over it.
It then had to be completely deconstructed and moved 3m before it was ticked off as being clear; its "checked and clear" status signified by a spraypainted circle around it.
It was a relatively simple system, but when you had such a big area, there were inevitably places that had to be redone, just to have the confidence they were done properly, Snr Sgt Benn said.
Teams had tried to be as sensitive as they could to people's property, while trying to complete the task at hand as fast as they could.
The job was immense and demanding, but he had enjoyed the challenge, he said.
"I like running searches. Most police like a good whodunnit; I like a good where-is-he."
He had done some USAR training, but that usually involved searching for just one person; nothing on the scale of the search in Christchurch.
The job involved a big responsibility both to be confident all buildings and piles had been cleared, and to try to ensure the security of people's properties.
The searchers were lucky to have had available the technology on board the fire service's command units, which were excellent for information management and made mapping the search area much easier, he said.
Although he had departed Christchurch last weekend after the official rescue effort became one of a recovery, the work on the area inside the remaining cordon continued.
There, many buildings were so dangerous the search effort was hampered by the need to semi-demolish parts of buildings before searchers could safely enter the rest.
He was scheduled to return to Christchurch this week but, with the recovery effort downgraded slightly, he was at present on standby if needed.
Many people in Dunedin wanted to go to Christchurch to help, and he was pleased he got the opportunity, he said.
"It's good to be able to help bring some order to chaos. That's what we do in the emergency services: we are always working from the unknown towards the known."