A year earlier, Somerville's neighbour Tisha Lowry went missing.
Despite a massive police investigation and the offer of a $20,000 reward there were no leads.
Tisha had vanished without a trace.
But the whole time, she was lying dead under the floor at the Somerville house - in a shallow grave beneath the living room.
In episode four of Herald podcast A Moment in Crime, we look back at the House of Horrors murders, and hear from the killer in his own words about what he did to the women and why.
This episode of A Moment In Crime contains material including references to violence, sexual assault and murder and might be distressing for some listeners.
Somerville pleaded guilty to two counts of murder soon after he was arrested and charged.
He was sentenced to life in prison and must serve 23 years behind bars before he is eligible for parole.
A Moment In Crime is written and hosted by Anna Leask, senior crime reporter for the Herald. The podcast is produced by Chris Tarpey. Frances Cook is the executive producer.
Leask has been covering crime and justice for the Herald for more than a decade and has reported on most of the major incidents and events over that time.
"Each month I'll take you inside some of our most infamous incidents, notorious offenders and behind the scenes of high profile trials and events to show you what's really happening in your backyard," she said.
"Heroes and villains battle for justice to be done, and it seems no matter how horrifying the story, we always want to know more.
"If you want to know more about the cases that have shocked and shaped our nation - from murders and massacres to violent villains and the utterly unbelievable - join me for A Moment In Crime."
In our first episode we looked back at the Christchurch terror attack - what unfolded on March 15 and how it changed New Zealand.
Despite exhaustive and repeated searches, there has never been any sign of the little girl.
To mark the 25th anniversary of Amber-Lee's disappearance, Leask investigated the famous cold case in a bid to generate some answers for the toddler's family.
It was the Herald's first true-crime podcast.
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