The brother of accused serial killer Bradley Robert Edwards insists his sibling is innocent.

Mr Edwards - a 50-year-old suspected of being the Claremont serial killer - is preparing to fight a string of murder and rape charges dating back to the late 1980s to the mid 90s.

His younger brother in the meantime penned an email to The Weekend West to say the family of the accused was behind him every step of the way.

'My brother is innocent and ... this will be made evident as the case unfolds,' the email read.

The brother of accused serial killer Bradley Robert Edwards (pictured) has broken his silence to defend his sibling's innocence

The immediate family has visited Mr Edwards in prison and spoken to him at every opportunity.

Though, they have been given legal advice to stay away from his court appearances.

Mr Edwards is accused of attacking an 18-year-old girl in her Huntingdale home in Perth in 1988 and allegedly raping a 17-year-old girl in Karrakatta Cemetery in 1995.

Police also allege he is responsible for the abduction and murder of Sarah Spiers, Jane Rimmer and Ciara Glennon from the upmarket Claremont suburb between January 1996 and March 1997.

Mr Edwards was arrested in December 2016 after forensic evidence allegedly linked him to the attacks.

At a pre-trial directions hearing last week, it emerged the prosecution wanted to use the DNA or fingerprint traces to connect Mr Edwards with the series of crimes.

The Supreme Court heard while Mr Edwards denied all the allegations brought against him in a six-hour interview with police, he failed to explain certain facts.

That is, he was unable to explain why traces of his DNA was found on a Kimono linked to the Huntingdale attack and also on two of his alleged victims.

He also couldn't explain why his fingerprints were found on a door of another Huntingdale home following an attempted break-in, the court heard.

Added to the list of the allegations is the abduction and murder of Sarah Spiers, Jane Rimmer (pictured) and Ciara Glennon from the upmarket Claremont suburb between January 1996 and March 1997

At a pre-trial directions hearing last week, it emerged the prosecution wanted to use the DNA or fingerprint traces to connect Mr Edwards with the series of crimes (pictured, Ciara Glennon)

Supreme Court Justice Stephen Hall noted the details brought to light during the pre-trial hearings were allegations - no evidence had been presented as of yet.

Barrister Paul Yovich said important questions had to be answered in relation to the forensic evidence.

'The question ... is, in each case, is it the accused’s DNA ... and if so, how did it get there?' he told the court.

'With count eight (Ms Glennon’s murder), are there other possibilities ... innocent contact, adventitious match or contamination in the collection or testing process?'

Mr Edwards is due back in court on March 20.