The widow of the math whiz who was killed in the lower Manhattan crane collapse in February is suing the city to preserve evidence in anticipation of a wrongful-death lawsuit.

David Wichs’ wife, Rebecca Wichs, is worried that the owner of the mangled equipment, Bay Crane, could tamper with the machinery if it’s not protected.

The crane is being held by the Department of Investigation.

Wichs’ suit asks the city to bar Bay Crane from inspecting its machinery without a court order. Her attorney, Howard Hershenhorn, said in court papers that the crane shouldn’t be inspected without participation from “all interested parties” to assure that no parts are “moved or manipulated.”

A city Law Department spokesman declined to comment. Bay Crane’s attorney did not return requests for comment.

David Wichs, 38, a mathematician at Tower Research Capital, was walking near his office on Worth Street when the 565-foot crane came crashing down on him. He died instantly.

Warning: Graphic content.