The Institution of Professional Engineers is no longer investigating the boss of the company which designed the failed CTV building.

Christchurch civil engineer Alan Reay owned Alan Reay Consultants - which designed the ill-fated building in 1986.

However, he resigned from IPENZ in February this year.

IPENZ Chief Executive Dr Andrew Cleland says after taking legal advice, they've concluded the investigations could no longer proceed.

As a membership body, IPENZ only has disciplinary jurisdiction over engineers who are members.

The Madras Street building collapsed during the February 2011 earthquake, killing 115 people.