Essex Police said a file is to be submitted “imminently” to the CPS for consideration following a “substantial and detailed investigation”.
A 50-year-old suspect, who has not been named, was arrested in Cheshire on March 17 after “significant new information” came to light, the force said.
He has since been released under investigation.
Butcher Mr Lubbock had been attending a party at Barrymore’s luxury home in Roydon on March 31, 2001 when he died.
A post-mortem examination showed the 31-year-old had suffered severe internal injuries which suggested he had been sexually assaulted.
Alcohol, ecstasy and cocaine were found in his bloodstream.
The coroner recorded an open verdict.
An Essex Police spokesman said: “Following our substantial and detailed investigation, we will imminently be submitting a file to the CPS for their consideration and decision.”