Comma.ai, the tech firm founded by hacker George Hotz, is facing federal investigation following five crashes involving its aftermarket driver assistance devices. Two of these resulted in fatalities, raising questions about the safety of hands-off driving tech.

The National Highway Traffic Safety Administration reported that the crashes occurred when the devices failed to detect or respond to slow or stopped vehicles in the same lane. Despite warnings, drivers must always be ready to take over, but the systems’ limitations are clear, especially with stationary objects.

One fatal incident in Ascension Parish, Louisiana, saw a Toyota RAV4, running FrogPilot, a modified version of Comma.ai’s software, collide with a fully marked police car. Two rear-seat passengers died. The other fatal crash, though not immediately identified, adds to the mounting concerns.

Comma.ai’s adaptive cruise control and automated lane centering systems aim to make driving less stressful, but their performance is limited by the presence of stationary vehicles. Tesla and Ford have faced similar investigations, highlighting the broader challenges in advanced driver assistance systems.