28/10/2011 11:46 BST | Updated 28/12/2011 05:12 GMT

Vincent Tabak: Young Professional Who Murdered Joanna Yeates Hid A Dark Psyche

"A totally detached crazy person" - Vincent Tabak unwittingly exposed his own psyche when asked at a dinner party who killed Joanna Yeates.

The 33-year-old does not fit the average mould set by other notorious killers.

He appeared to be excelling in both his professional and personal life after moving to the UK from his Dutch home town of Uden.

Friends told how he fitted seamlessly in the upmarket Bristol district of Clifton where he lived with "the love of his life" Tanja Morson.

Yet behind her back he was leading a depraved sex life, watching violent pornography and setting up meetings with prostitutes.

Educated to PhD level, Tabak, who has older brothers and sisters, was marked out as a hard-working and sociable employee at consultant engineer firm Buro Happold.

Solicitor Sarah Maddock, a mother-of-two who is one of Miss Morson's closest friends, said Tabak and Miss Morson were planning marriage.

The 6ft 4ins killer was described as quiet, mild-mannered and tactile with his girlfriend.

Both Tabak and Miss Morson worked long hours and would commute each day.

His daily routine involved him cycling to Bristol Temple Meads each morning where he would catch the train to his office in Bath.

US-born Miss Morson travelled to her workplace at the Dyson headquarters in Malmesbury, Wiltshire.

Friends described them as outgoing, hard-working and keen to start a family.

They had spent the summer regularly attending music gigs. Tabak was among the revellers at the End of the Road music festival, a source said.

Photos on Facebook showed him enjoying numerous nights out and posing in a purple skirt, a floral top and a straw hat with pink feathers at a music festival.

Another showed him smiling with Miss Morson during a visit to Stonehenge.

Tabak was born in Veghel and obtained a masters degree and a doctorate at Eindhoven University before coming to Britain in 2007.

In his PhD thesis, Tabak refers to missing his dead father.

He writes: "I miss you and regret that you are not able to see the end result of my PhD."

"Last but not least, I want to thank my girlfriend Tanja Morson for her support in the last difficult month of my PhD. I am very happy that she entered my life."

Having met Miss Morson through the Guardian Soulmates website in 2008, the couple built up a circle of friends, regularly attending dinner parties.

Tabak killed Miss Yeates just weeks after returning from Los Angeles, where he had been working for several months.

Losing Miss Morson, who had been his first serious girlfriend since arriving in Britain, was Tabak's biggest fear after strangling his next-door neighbour.

In the weeks that followed, Tabak lost more than a stone in weight as he exercised heavily and struggled to sleep.

But none of his new friends noticed a change in his behaviour.

At a dinner party with Ms Maddock, who attended Exeter University with Miss Morson and had briefly lived with her in New York in 2001, bespectacled Tabak was said to seem "relaxed and happy".

"Vincent was his usual calm and quiet self," she said.

But now Tabak has been exposed as a calculated liar with a depraved obsession with violent sex.

Even his own QC William Clegg said could offer no excuses for Tabak's attempts to avoid justice.

In Mr Clegg's own words Tabak had been "frankly disgusting".

And Miss Morson seems seems to agree, having failed to make a single appearance at Bristol Crown Court.

The loving couple, it seems, are no more.