The widow of a man killed by the driver of a speeding car wants a much heavier punishment of up to 20 years for the criminal offense of dangerous driving, not seven years for negligent driving.

Sasaki Taeko and her lawyer made the appeal at a news conference in Tokyo on Friday.

Her husband, Kazutada, died when his motorcycle was hit from behind by a passenger car that was traveling at more than 160 kilometers per hour in Utsunomiya City, north of Tokyo, in February.

The 20-year-old driver is standing trial for negligent driving resulting in death.

Sasaki argues the defendant should be charged with dangerous driving as he was driving at a speed far exceeding the legal limit of 60 kilometers per hour.

Her lawyer said prosecutors could have determined that the defendant was driving recklessly, judging from footage of a dashboard camera and security cameras along the road.

Sasaki has launched a petition, including one online, to demand heavier punishment. More than 60,000 people have signed up, and a portion of the signatures have been submitted to the public prosecutors' office.

Sasaki says many people are supporting her cause, and she wants more people to know about this case. She and her supporters plan to collect more signatures from the public in Tokyo this weekend.