POLICE have released a graphic detailing the four-week investigation into the death of Southampton school girl Lucy McHugh.

In a statement it said: "It is four weeks since the body of Southampton teenager Lucy McHugh was found and our dedicated team of officers and staff has been working tirelessly to catch her killer.

"Today we are releasing a timeline of key points in our murder investigation in the hope that this will help jog people’s memory and someone may come forward with information which could be vital."

Daily Echo:

Lucy's body was found in a wooded area a month ago.

Since the discovery, at Southampton Sports Centre on July 26, Hampshire Constabulary have launched what officers have described as one of the 'biggest investigations' in the force's history.

But what do we know so far about the police investigation.

Here we breakdown the information...

When and where was Lucy found?

Lucy McHugh's body was found in a wooded area of Southampton Sports Centre at 7.45am on Thursday, July 26.

The 13-year-old was located near to a cricket pitch and the Alpine Sports Centre of the facility.

What happened next?

Police cordoned off the area later confirmed they had launched a murder investigation.

The cordon remained in place for several days and thorough search was conducted of the area around where Lucy's body was discovered.

On two occasions, members of the public banded together to help search the ground of the Sports Centre for a murder weapon.

Police believe a bladed article, perhaps a knife or scissors, were used in the murder.

They also searched Lucy's home in Mansel Road East and another home on the same road.

Police were later spotted searching an area of nearby Hollybrook Cemetery.

How did the community react?

At first shock, later grief and at times anger and frustration.

The news of Lucy's death and the subsequent murder investigation was quickly shared by hundreds of people via Facebook and Twitter and Hampshire Constabulary says its appeal has since reached more than one million people.

Soon after the news was broken, a fundraising page was set up to help pay for Lucy's funeral.

It aimed to raise £5,000, but as of yesterday, the page had raised more than £7,000.

A balloon release was later conducted at Mansel Park, near to Lucy's home, by her friends.

Her headteacher at Redbridge Community School, Jason Ashley, also paid a touching tribute the 13-year-old and expressed his shock at her death.

What was Lucy wearing?

The main focus of the police's appeal began with sightings of Lucy in the period between 9am on Wednesday, July 25, when Lucy was last seen at her home in Mansel Road East and 7.45am on Thursday, July 26, when her body was found.

Police released images of the clothing Lucy was wearing.

Officers say she was wearing a black jacket with white sleeves, with the logo for the band Falling in Reverse on the front and RADKE 01 in red on the back.

She was wearing a white top, camouflage coloured leggings and black Nike Jordan trainers.

Sightings of Lucy

At first, little was known about Lucy's movements between her last sighting and her body being discovered.

But last week, police made a breakthrough in their investigation - uncovering CCTV of the 13-year-old as she walked by a convenience store near to the Sports Centre.

CCTV captured the moment Lucy walked past the Tesco Express store on the coroner of Coxford Road and Lordswood Road at 9.30am on Wednesday, July 25.

The store is a short walk from where Lucy's body was discovered.

It remains the last sighting of Lucy to date.

Yesterday, police released more CCTV of the teenager walking past Premier Convenience Store on Wimpson Lane, taken at 9.06am on Wednesday, July 25.

CCTV also showed her walking on Coxford Road past Southampton General Hospital around 9.25am that same morning.

Police are still appealing for sightings of Lucy and anyone who may have been seen acting suspiciously around the Sports Centre that morning.

The size of the police investigation

Detective Superintendent Paul Barton, the man leading the probe, has described it as one of the biggest in recent history at Hampshire Constabulary.

Officers continue to sift through more than 15,000 hours of CCTV footage from more than 250 locations.

They've also collected more than 900 items and received over 200 reports from members of the public.

Almost 200 officers have been involved in the investigation.

And this week, Hampshire Constabulary enlisted the help of officers from the National Crime Agency (NCA), further bolstering the resources at their disposal.

Have police made an arrest?

Yes. Police originally arrested a 24-year-old man on suspicion of murder and engaging in sexual activity with a child.

They were later granted an extension to continue questioning the suspect.

Police then bailed the 24-year-old, from Southampton, pending further investigation.

But the same man was immediately arrested and charged on suspicion of a charge which relates to failing to disclose a password to his Facebook account to detectives investigating Lucy’s murder.

He was remanded in custody until August 31.

Can you still help the police?

Absolutely. Police are still actively appealing for people to come forward and help their investigation.

Crimestoppers has offered a £10,000 reward for information leading to the arrest and conviction of the person responsible for Lucy's murder.

Emily van der Lely, Crimestoppers spokeswoman, said: “This is every family’s worst nightmare, to have their child taken away from them at such a young age, it’s heartbreaking."

What next?

Police have admitted they are struggling in one particular area of the investigation - and that's the location where her body was found.

Det Supt Barton said:"The fact that we are now struggling in the location of where she was found because there is no CCTV, that may well have been an intended area for Lucy to meet her killer.

"I think she was walking past Tesco Express on the morning of the 25th with purpose and I think she was going to meet somebody - and I think that was the person who killed her.

"There is no CCTV and there is no telephone we can rely upon and there are no clear eye-witnesses, so that presents us with a real challenge - but we haven't given up."

One thing the police are appealing for is for people who may have seen someone acting suspiciously in the area around the Sports Centre.

Det Supt Barton said: "We want readers to focus on the area of the Sports Centre.

"Were you there on that day? Did you see Lucy?

"More importantly, did you see a suspect or did you see someone who was coming away from the scene?

"Maybe they were in a hurry or in distress?

"If you were there please pick up the phone and call us now."