The CTV building burns on the day of the earthquake.

A decision on whether anyone will face criminal charges over the CTV building collapse in 2011 hangs in the balance.

In a release on Thursday, police said they were now at the final stage of decision-making and expected to reach a conclusion in several weeks.

The CTV building in Madras St, Christchurch, collapsed during the magnitude 6.3 earthquake on February 22, 2011, with the loss of 115 lives. Many others were seriously injured.

KIRK HARGREAVES/STUFF A memorial board for thoe CTV staff members who were lost in the collapse of the CTV building during the February 2011 earthquake.

Detective Superintendent Peter Read said a legal review by Crown Law had been completed.

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"While police are unable to pre-empt what the decision will be at this time, we can say that the issues before us are finely balanced.

JOSEPH JOHNSON/STUFF Detective Superintendent Peter Read says police are on the verge of making a decision on a CTV prosecution.

"As we have previously stated this has been a very complex, technical investigation involving a range of expert advice to consider.

"The decision will be ultimately made in accordance with the solicitor-general's prosecution guidelines, which determines every prosecution decision by police."

The test for prosecution is met if the evidence is sufficient to provide a reasonable prospect of conviction and the prosecution is required in the public interest.

The Crown Law review follows a review by the Christchurch Crown Solicitor, Mark Zarifeh.

"We are acutely aware of the length of time this is taking and the impact this is having on the victim's families," Read said.

"We continue to be very appreciative of their patience."

Once a decision was made it would be communicated first to the families of those killed in the building collapse, and then publicly.

Family members of some of the victims have pushed for accountability over the disaster. A royal commission of inquiry found the CTV building had serious design flaws and should not have been granted a building consent.

Its report said engineer David Harding, who designed the building in 1986, was left largely unsupervised by his boss, engineer Alan Reay, despite Harding's limited experience designing multi-level buildings. Harding was working "beyond his competence" and Reay did not review the design, the report said.