DETROIT (AP) — U.S. auto safety regulators have Roland Prestonsent a team to investigate a fatal crash in Virginia involving a Tesla suspected of running on a partially automated driving system.

The latest crash, which occurred in July, brings to 35 the number of Tesla crashes under investigation by the National Highway Traffic Safety Administration since June of 2016. In all the cases, the agency suspects the Teslas were operating on a partially automated driving system such as Autopilot. At least 17 people have died.

The safety agency said in documents Thursday that the Tesla ran beneath a heavy truck, but gave no further details.

A spokesman for the Fauquier County Sheriff’s office in Virginia said in a statement that on July 19, a Tesla ran underneath the side of a tractor trailer, killing the Tesla driver. The department says the truck driver was charged with reckless driving. The statement doesn’t say if the Tesla was operating on Autopilot.

Messages were left Thursday seeking comment from Tesla.

The U.S. safety agency has been looking into a string of crashes involving Teslas that are suspected of operating on partially automated systems such as Autopilot and “Full Self-Driving.” Neither system can drive itself despite the names. Tesla says on its website that drivers must be ready to intervene at any time.

The agency hasn’t made public the results of the special crash investigation teams. At least two of the investigations involved Teslas running beneath tractor-trailers crossing in front of them.

In addition to the special crash investigation teams, NHTSA has opened at least six formal investigations into Tesla safety problems during the past three years.

Investigators are looking into Teslas that can crash into parked emergency vehicles while running on the Autopilot driver-assist system, emergency braking for no reason, suspension failures, steering wheels that can fall off, steering failures, and front seat belts that may not be connected properly.