Driver hit with new charges over death of top cop's son

Charlie Stevens, 18, sustained an irreversible brain injury after being run down about 9pm on Friday in Goolwa, about 90km southeast of Adelaide, an emotional SA Police Deputy Commissioner Linda Williams told reporters.

Police said the 18-year-old driver failed to stop at the scene but was found nearby and charged with several offences on Saturday.

On Sunday, those charges were upgraded to causing death by dangerous driving, aggravated driving without due care, leaving the scene of a crash after causing death and failing to truly answer questions.

The man was refused bail and will face Christies Beach Magistrates Court on Monday.

Police said Charlie died surrounded by family and friends about 7pm on Saturday.

In a statement, Commissioner Grant Stevens and his wife Emma thanked police, first responders and other emergency services workers who attended the incident.

"The Stevens family also wish to thank the wider community for their support during this difficult time in particular the family acknowledge the dedicated staff at the Flinders Medical Centre for their care and support of Charlie and his family and friends," they said.

Premier Peter Malinauskas said the thoughts of all South Australians were with Mr and Mrs Stevens and their children.

"Grant Stevens has served South Australia as a member of South Australian Police for over 40 years," Mr Malinauskas said.

"His whole life he has dedicated himself to protecting others, protecting South Australians from evil, protecting us from disease.

"He has shown extraordinary leadership in some of the most difficult circumstances this state has ever confronted, and it is just so unjust that he and his family have now had to endure this great tragedy themselves."

Major crime detectives continue to investigate the Goolwa incident.

Australian Associated Press