A wild-haired fugitive accused of viciously stabbing a policeman has been covering up to 30 kilometres a night on foot and has "exceptional bushcraft skills", police say.

A member of the public spotted James D'Zilva just after midnight last night at Yarra Glen, but by the time police arrived he had vanished, the latest disappearing act in his 10 days on the run.

It came as a more detailed picture emerged of the 32-year-old homeless man, who is accused of stabbing a police officer eight times at a petrol station in Healesville on December 7.

Superintendent Jeff Forti said D'Zilva suffered from disorganised schizophrenia, resulting in irrational thinking, delusions and paranoia.