The Hampshire teenager who plunged to her death from an M27 bridge on Saturday had claimed she was the victim of a sex attack only days earlier.

Sara Clark's grieving family claim the 18-year-old committed suicide because she thought police did not believe her story.

Hampshire police have revealed that an independent inquiry had been launched into Sara's death and her allegations of a sex attack.

Her body was discovered on the westbound carriageway of the M27 beneath Hill Street bridge near junction two early on Saturday.

He parents say that Sara had been upset because, she had not received any follow-up calls from police or counsellors after making her a complaint of sexual assault as she walked through Testwood Recreation ground last Wednesday.

Mother Amanda, 44, said: "They promised to come back to her the next day. They didn't. If only they spoke to her she would be alive today."

Before her death Sara had left the family home in Calmore at about 3am after loading up her new iPod with songs and using an online messaging service on her computer.

Earlier her parents had both gone to bed, leaving their daughter in a "quite happy" mood.

But the following morning her dad Howell, 50, was shocked to discover the body was his daughter after hearing a familiar description on the radio, finding her room empty and visiting the bridge. Sara had not left a note or message.

Mr Clark said: "I certainly didn't expect what happened. Evidently she felt she wasn't being believed or was being ignored.

He added: "She probably had the feeling nobody cared about her."

Mr Clark, a computer engineer, said he had no doubt his daughter had been raped earlier in the week.

He said she had returned by bus early on Wednesday after a night out in Southampton with friends.

She was walking alone past the Testwood Recreation ground in Salisbury Road, about a mile from her home, when a man came from behind and sexually assaulted her, Mr Clark said.

Sara alerted police from the scene and was then interviewed at Totton police station before being taken to the Treetops sexual assault referral centre in Cosham at 5am for medical tests and more interviews.

Sara left at about 10.30am and had further blood tests at the Royal South Hants Hospital in Southampton before two detectives interviewed her alone at home in late afternoon.

Mrs Clark, a cleaner, told how her daughter had then confined herself to the home, only venturing out accompanied for cigarettes.

Mrs Clark said Sara was just waiting around for a call from the police: "She was getting so depressed and low. They didn't bother getting in touch.

"Why didn't they call back even just to say they were still investigating?"

Paying tribute to their daughter the Clarks described her as "a happy bubbly person" who was "really outgoing", and "nice to be around".

They said Sara had been suffering from depression for some time following a split with her boyfriend.

The former Testwood School pupil, who left at 16, moved back to her parents house from her Southampton city flat six months ago.

She enjoyed music, reading and quiz books, visiting old battlefields with her father and had four pet cats.

Her sister Sabrina, 24, lives in West End, while her brother Steven, 22, lives in Wales.

The Clarks praised the local police beat and family liaison officers for comforting them and keeping them informed following Sara's death.

A post-mortem examination carried out by a Home Office pathologist revealed Sara died from head injuries. Police have said they are not treating her death as suspicious.

Det Insp Kath Barnes from Hampshire police said in a statement: "We can confirm an allegation of sexual assault was reported on May 30.

"Police are in the process of thoroughly investigating this allegation and as a matter of routine, information has now been passed to the Independent Police Complaints Commission."

She added professional standards rules meant because Sara had spoken to detectives shortly before her death the matter had to be reported. She declined to comment further.

The Home Office's code of practice for victims of crime, which sets out the services they can expect to receive from the criminal justice system, includes a right to information about their crime.

It says the police must notify the victim on at least a monthly basis, of progress in cases being actively investigated up until the point of closure of the investigation.

If you knew Sara you can leave a message of condolence on our website www.dailyecho.co.uk