Jim Dickie spoke ahead of a Parole Board decision this week on whether the 69-year-old killer should be let out of Full Sutton Prison in York.
Cannan is serving three life sentences after being convicted in 1988 of the murder of Shirley Banks, plus multiple other sexual offences.
On October 8, 1987, he abducted the newlywed 29-year-old in Bristol, before raping and killing her.
But he is also the prime suspect
in the Lamplugh case. Suzy disappeared on July 28, 1986, after arranging to meet a client called
Mr Kipper in Fulham, west London.
She was never seen again and no body has been found. Mr Dickie revealed forensics experts are using technology to grow DNA in a lab sourced from a smudged fingerprint on the rear view mirror of Suzy’s car that could identify her killer.
The former detective superintendent, in charge of a 2000-06 inquiry into Suzy’s disappearance, is convinced Cannan remains a danger.
“I don’t think he should ever be released,” he said.
“He is a psychopath.”
A man believed to be Cannan was seen getting out of a taxi by a
witness in Fulham Broadway the morning Suzy, right, disappeared.
The man was seen the day before looking through a nearby estate agency window by another witness.
Cannan was freed from a seven-year sentence for rape on July 25, three days before Suzy went missing.
Interviewed twice by police,
Mr Dickie said: “He was quite uncomfortable as he had no alibi.”
Cannan has also been connected to the May 3, 1986 abduction and murder of Sandra Court, 29. He had been on day release at the time.
He has never been charged, although efforts were made to charge him with Suzy’s death. However the CPS decided against it.
A spokesman said the case was archived so they could not comment but “any decision will have been made in line with our legal test”.
● Mr Dickie has requested his fee for this article go to the Suzy Lamplugh Trust, www.suzylamplugh.org
