Police watchdog says threshold was not met for an independent investigation into the collision.
Devon and Cornwall Police are continuing their investigation into a serious collision on North Hill involving an electric motorbike that left a 19-year-old man seriously injured.
The crash happened on the evening of Thursday, 30 April.
Officers had initially been called to the Devonport area at around 11.40pm following reports of a group on electric motorbikes allegedly attacking a vehicle while in possession of weapons.
Shortly afterwards, emergency services were called to a separate collision at the junction of North Hill and North Road East, involving an electric motorbike and a car which was not connected to the original incident.
The 19-year-old rider suffered serious injuries and was taken to Derriford Hospital for treatment. The road was closed while emergency services dealt with the incident.
Images circulated on social media after the crash appeared to show what looked like a meat cleaver lying in the road close to the abandoned electric motorbike. The images have not been independently verified.
Because police officers had been operating in the wider area before the collision, Devon and Cornwall Police made a mandatory referral to the Independent Office for Police Conduct (IOPC).
Plymouth Live has reported that the IOPC received the referral before assessing the information available and returning the matter to Devon and Cornwall Police.
The IOPC concluded that the threshold for an independent investigation had not been met.
The watchdog said there was no evidence of physical or tactical contact between police and the rider before the collision, and that the crash happened outside the officers’ view.
It concluded there was insufficient evidence at that stage to indicate that police actions may have caused the collision.
The IOPC has reminded Devon and Cornwall Police that the matter should be referred again if new information emerges relating to professional standards or possible criminal offences.
Devon and Cornwall Police have confirmed that their investigation into the collision remains ongoing.
Photographs © Wayne Perry / Plymouth Post