The parents of murdered teenager Alice Gross are urging political groups not to "hijack" their daughter's death for their own anti-immigration policies.
The 14-year-old was found dead in west London's River Brent one month after she was reported missing. The main suspect in her murder, Latvian Arnis Zalkans, was found hanged shortly afterwards.
The Crown Prosecution Service confirmed had he still been alive, Zalkans would have been charged with the teenager's murder, with police also believing the evidence in the case "points firmly" to him being responsible.
Zalkans, 41, arrived in Britain in 2007 despite serving a seven-year sentence for murdering his wife in his native Latvia. Metropolitan Police confirmed he had arrived in the UK legally, but Alice's parents said they have "serious unanswered questions" and are now calling or an inquest into whether he should have ever been allowed to enter at all.
However, the Gross family said they and their daughter believed in the free movement of people and do not want Alice's case "hijacked by groups with an anti-immigration agenda".
Alice's parents, Jose Gross and Rosalind Hodgkiss, added: "Although we now have certain information about how Alice died, we are still left with a number of serious unanswered questions about what the authorities knew or should have known about the man who is believed to have killed our daughter when he came to the UK.
"Alice believed in the free movement of people and so do we.
"For her sake we are determined to ask these questions responsibly and sensitively."
Emma Norton, a legal officer for civil rights group Liberty, is representing the family at the upcoming inquest.
She said: "Liberty has made representations to the coroner that the inquest into Alice's death must be an Article 2 inquest - that is, an inquest that will look not only into the cause of her death, but also into the wider circumstances.
"In particular, the family wants to know what the authorities knew or ought to have known about Zalkalns when he travelled to the UK from Latvia.
"The family is aware that this is a sensitive and difficult subject, and is concerned to ensure that it is not hijacked by groups with an anti-immigration agenda.
"The family believe in freedom of movement and human rights. That is why they approached Liberty and asked us to help them.
"We hope the coroner will agree that there are important questions that need to be answered, and we are waiting to hear from him."
A date has yet to be decided for when the opened and adjourned inquest will resume.
The body of Zalkans was found hanged on 4 October just five minutes from the canal path where Alice was last seen alive.
Her body was found wrapped in a bag and weighted down by logs and house bricks. Police believe the motivation behind the murder was "most likely sexual".
In 2009, Zalkans was arrested over an alleged indecent assault on a 14-year-old girl. The case against him was dropped after the girl declined to make a statement.