The deadly collapse in 2023 of a parking garage in New York City's lower Manhattan was caused by faulty design almost a century ago, dereliction over the years and unauthorized construction more recently, according to the conclusions of a forensic investigation.

The collapse killed one person — a worker — and injured five others after the garage, on a busy block at 57 Ann St., just blocks from the seat of New York City government.

When the garage collapsed, there were six workers inside, four of whom were brought to hospitals. The person killed was a worker in the garage.

About a year after the collapse, the City Council passed legislation tightening regulations around parking garages, including requiring the Department of Building to study the condition of garages, beyond existing and ordinary inspections, shorten the inspection schedule, and increase penalties for violations.

Newsday reported last year that the city had contracted with LERA Consulting Structural Engineers, at a cost of $990,240.47 to undertake a forensic investigation of the collapse.