Investigators probing the private jet crash that killed seven people at Hanscom Field on May 31 have finished their documentation of the crash scene and left the area, the National Transportation Safety Board said Tuesday.

A board spokesman said that a preliminary report could be issued by the end of this week, but cautioned that it will not outline potential causes of, or factor in, the accident. The report will only discuss “verified factual information that has been established at this very early stage in an investigation that is expected to last at least 12 months,” NTSB spokesman Peter Knudson said in a statement.


Work documenting the scene was finished on Saturday, Knudson said.

He said investigators have formed groups looking into the following areas: survival factors, airworthiness, operations, aircraft performance, flight data recorder, and cockpit voice recorder.

The NTSB said last week that the Gulfstream IV jet reached a speed of 190 miles per hour before slowing down and hurtling into a gully. The plane’s flight data recorder showed that the brake pressures were rising and the thrust reversers were engaged, another sign the pilots were trying to stop. Experts said those two facts suggested the pilots were desperately trying to stop the plane.

The NTSB also said the cockpit voice recorder captured comments about “aircraft control” at the moment that the pilot was supposed to pull the plane’s nose up and take wing. The NTSB would not say what the comments were.

Philanthropist Lewis Katz, co-owner of the Philadelphia Inquirer, died in the crash, along with three guests and three crew members.

Martin Finucane can be reached at martin.finucane@globe.com.