MEXICO CITY — Investigators said today that they have found evidence of irregularities in the training records of the pilots handling a jet that crashed earlier this month, killing Mexico’s interior secretary.

Investigators had previously pointed to instability caused by the wake turbulence of a Boeing 767-300 as the likely cause of the Nov. 4 crash of the Learjet 45.

However, they also say the pilots appeared unfamiliar with flight controls or procedures, and on Friday officials filed an administrative complaint with the federal office overseeing public servants.

Transportation Secretary Luis Tellez said the training records show the lack of a qualified instructor, and improperly registered qualifying hours of flight.

Tellez did not say who was named in the complaint, but he said the probe will focus on government officials who are supposed to oversee compliance with pilot flight-training and certification.

Most flight-training for such aircraft in Mexico is carried out by private firms, with government regulation.

A total of 15 people — those on board the plane, including Interior Secretary Juan Camilo, and several people on the ground — were killed when the jet smashed into a wealthy Mexico City neighborhood.

A transcript of the cockpit recorder suggest the frantic pilots were struggling to regain control of the plane before they crashed.

A preliminary investigation found the pilots were slow to follow the control tower’s instructions to reduce speed and appeared to be nearly one nautical mile too close behind the larger plane on the same flight path to Mexico City’s international airport.