Joanna Yeates may have been held captive before her murder

After detectives confirmed yesterday that Joanna Yeates was strangled, her father said that he believes the police know more about the landscape architect's death than they are telling the family.

Ms Yeates, 25, who was missing for more than a week before she was found – frozen and covered in snow, by dogwalkers on Christmas morning – had died several days before as a result of "compression of the neck", a post-mortem examination has revealed. Her body was recovered about three miles from her flat in Bristol.

David Yeates, 63, told the Southern Daily Echo: "We are sure the police know more about what happened than they are telling us, but at the moment we are not questioning them because we feel they are doing their best."

His comments came as detectives officially opened a murder inquiry and said that they were keeping an "open mind" as to possible theories or motives. Many unanswered questions remain.

"We now know how she died," said Detective Chief Inspector Phil Jones, of Avon and Somerset Police. "What we have to do next is find out why she was killed and who was responsible."

Ms Yeates was last seen on 17 December when she left friends at the Ram pub to walk to her home in the Clifton area of Bristol. She then went to a Tesco store where she was captured on CCTV buying a pizza.

Yesterday it was revealed that she had also visited a Bargain Booze store next door, where she bought a small bottle of cider.

She is then believed to have returned to the flat she shared with her boyfriend on Canynge Road – her coat, purse, mobile phone and keys were all found there, as well as a receipt for the pizza. But neither the pizza nor its packaging have been recovered. Det Ch Insp Jones was unable to say yesterday whether or not examination of Ms Yeates's stomach contents had established if she had eaten the pizza.

Given that there was no sign of forced entry to the flat, one line of inquiry officers are pursuing is that Ms Yeates knew her killer. Police are also investigating the possibility that Ms Yeates may have been held captive.

Det Ch Insp Jones reiterated that Ms Yeates's boyfriend, Greg Reardon, who raised the alarm that she was missing on 19 December after returning from visiting family in Sheffield, was being treated as a witness and not as a suspect. The officer confirmed that Mr Reardon's laptop and mobile phone had been examined, but that this was standard procedure.

Yesterday Det Ch Insp Jones said that he believed Ms Yeates's body had been dumped on the roadside verge "several days" earlier. The officer also confirmed that Ms Yeates was fully clothed when discovered, but did not rule out a sexual motive to her death.

Police are continuing to review hours of footage from the 32 CCTV cameras which monitor Clifton Suspension Bridge, the main road link between Ms Yeates's flat and where she was found.

Yesterday Mr Yeates said: "Hearing Jo had been murdered was not a surprise because we had been told to prepare for the worst."

But, he added: "I fear that whoever has done this will never hand themselves in but we live in hope that the police will catch who is responsible.

"Since hearing about her death, all sorts of things have been running through our mind and we are trying to rationalise what has happened.

"Last week was the worst of our lives and we are hoping that we will never have to go through anything like this again."

He added: "Things were made just that little bit less terrible when we saw Jo's body. It was a relief to see her again – we just said: 'Welcome back'."

Suggested Topics
Start your day with The Independent, sign up for daily news emails
ebooksA celebration of British elections
Arts and Entertainment
Billie Piper as Brona in Penny Dreadful
tvReview: It’s business as usual in Victorian London. Let’s hope that changes as we get further into the new series spoiler alert
Life and Style
A nurse tends to a recovering patient on a general ward at The Queen Elizabeth Hospital in Birmingham
Arts and Entertainment
No Offence
tvReview: No Offence has characters who are larger than life and yet somehow completely true to life at the same time spoiler alert
Chuck Norris pictured in 1996
Arts and Entertainment
Sarah Lucas, I SCREAM DADDIO, Installation View, British Pavilion 2015
artWhy Sarah Lucas is the perfect choice to represent British art at the Venice Biennale
A voter placing a ballot paper in the box at a polling station
Arts and Entertainment
The Queen (Kristin Scott Thomas) in The Audience
theatreReview: Stephen Daldry's direction is crisp in perfectly-timed revival
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?

Day In a Page

General Election 2015: Ed Miliband's unlikely journey from hapless geek to heart-throb

Miliband's unlikely journey from hapless geek to heart-throb

He was meant to be Labour's biggest handicap - but has become almost an asset
General Election 2015: A guide to the smaller parties, from the the National Health Action Party to the Church of the Militant Elvis Party

On the margins

From Militant Elvis to Women's Equality: a guide to the underdogs standing in the election
Amr Darrag: Ex-Muslim Brotherhood minister in exile still believes Egypt's military regime can be replaced with 'moderate' Islamic rule

'This is the battle of young Egypt for the future of our country'

Ex-Muslim Brotherhood minister Amr Darrag still believes the opposition can rid Egypt of its military regime and replace it with 'moderate' Islamic rule, he tells Robert Fisk
Why patients must rely less on doctors: Improving our own health is the 'blockbuster drug of the century'

Why patients must rely less on doctors

Improving our own health is the 'blockbuster drug of the century'
Sarah Lucas is the perfect artist to represent Britain at the Venice Biennale

Flesh in Venice

Sarah Lucas has filled the British pavilion at the Venice Biennale with slinky cats and casts of her female friends' private parts. It makes you proud to be a woman, says Karen Wright
11 best anti-ageing day creams

11 best anti-ageing day creams

Slow down the ageing process with one of these high-performance, hardworking anti-agers
Juventus 2 Real Madrid 1: Five things we learnt, including Iker Casillas is past it and Carlos Tevez remains effective

Juventus vs Real Madrid

Five things we learnt from the Italian's Champions League first leg win over the Spanish giants
Ashes 2015: Test series looks a lost cause for England... whoever takes over as ECB director of cricket

Ashes series looks a lost cause for England...

Whoever takes over as ECB director of cricket, says Stephen Brenkley
Fishing for votes with Nigel Farage: The Ukip leader shows how he can work an audience as he casts his line to the disaffected of Grimsby

Fishing is on Nigel Farage's mind

Ukip leader casts a line to the disaffected
Who is bombing whom in the Middle East? It's amazing they don't all hit each other

Who is bombing whom in the Middle East?

Robert Fisk untangles the countries and factions
China's influence on fashion: At the top of the game both creatively and commercially

China's influence on fashion

At the top of the game both creatively and commercially
Lord O’Donnell: Former cabinet secretary on the election and life away from the levers of power

The man known as GOD has a reputation for getting the job done

Lord O'Donnell's three principles of rule
Rainbow shades: It's all bright on the night

Rainbow shades

It's all bright on the night
'It was first time I had ever tasted chocolate. I kept a piece, and when Amsterdam was liberated, I gave it to the first Allied soldier I saw'

Bread from heaven

Dutch survivors thank RAF for World War II drop that saved millions
Britain will be 'run for the wealthy and powerful' if Tories retain power - Labour

How 'the Axe' helped Labour

UK will be 'run for the wealthy and powerful' if Tories retain power