It is highly unusual for a dog-mauling death to result in a murder trial, but then again the case against Marjorie Knoller and Robert Noel has unusual written all over it.

The married couple, both lawyers from San Francisco, were not just the owners of the Presa Canario attack dog that killed their neighbour Diana Whipple, a 33-year-old school lacrosse coach, in January last year.

They were involved with a neo-Nazi gang serving hard time at one of California's maximum security prisons, and apparently raised Presa Canarios on their behalf. They even adopted one of the gang members, Paul "Cornfed" Schneider, as their son shortly after Ms Whipple's death.

And it gets weirder. According to letters and other documentary evidence presented in court, Ms Knoller sent naked pin-up photos of herself to Schneider and considered him her second husband. Prosecution lawyers say they also have evidence that the defendants used the dogs for sexual gratification – a charge so incendiary that it is not clear whether the judge can allow it to be brought before a jury.

More immediately, the couple have not shown the slightest hint of remorse. In a letter to Schneider cited by the prosecution, Mr Noel boasted proudly that his dog Bane – the same one that later killed Ms Whipple – had attacked a blind woman in the street. Ms Knoller admitted to a grand jury that she did not call for help after she saw Bane tear at Ms Whipple's throat on the corridor between their respective apartments, but rather concentrated on fishing her keys out of her handbag.

This is a story that has kept San Francisco transfixed ever since it broke a year ago, a story in which the couple, in the words of prosecuting lawyer James Hammer, "blurred the boundaries between dog and human... with fatal consequences". They have denied any wrong-doing.

Because of the publicity, the trial has been transferred to Los Angeles, where jury selection began this week. Both defendants are charged with manslaughter and keeping a dangerous animal. Ms Knoller is further charged with second-degree murder, making this case something of a first: no dog-mauling case in California has resulted in a murder conviction before.

The prosecution admits the burden of proof is daunting. "The odds are stacked way against us on murder," Mr Hammer acknowledged in court last week. Nevertheless, the extraordinary circumstances of the case virtually guarantee an irresistible spectacle once the full trial gets under way next month. Even if the court cannot convict the couple on the more serious charges, public opinion almost certainly will.

Consider the evidence. A couple of weeks before her death, Ms Whipple came face to face with Bane and was apparently scared out of her wits – an incident that Mr Noel wrote up gleefully to Mr Schneider, describing his neighbour dismissively as a "timorous, little mousy blonde". In the same letter, Mr Noel alluded to the unusual sexual arrangement between the various protagonists. "I wanted to thank you for the thoughts expressed about your feelings about how comfortable you would feel about Marjorie and I inhabiting your body and mind," he wrote.

After Ms Whipple's death, Mr Noel wrote at length to the San Francisco District Attorney's office suggesting that she had brought about her own demise because her perfume had given off pheromones that whipped Bane into a frenzy. On the day that the indictments were handed down, last March, both defendants took off in their car, drove so fast they got a speeding ticket, and were eventually stopped and arrested in a tiny town four hours north of San Francisco. Unable to make bail, set at $1m (£710,000) each, they have been in pre-trial custody ever since.

On the bestiality question, the prosecution has not been explicit about the nature of its evidence. Ms Knoller's lawyer, Nedra Ruiz, has dismissed the accusation as "specious filth" but stopped short of entirely denying it. "Your honour, there is no sex in this case, in terms of the touchy-feely stuff that that word normally invokes," she said last week.

It is clear from their previous statements that the defendants' worst enemies in court are likely to be themselves.