Kayleigh Haywood is described as about 5ft 6in (1.7m) tall, of medium build with mousey-coloured long hair
Police have said they are now treating the disappearance of Leicestershire teenager Kayleigh Haywood as murder.
The 15-year-old, from Measham, has not been seen since about 18:00 GMT on Friday when she was dropped off outside Ibstock Community College.
Police said the find of the teenager's mobile phone and belongings, alongside other information had led them to believe she has been killed.
Two men, aged 27 and 28, have been re-arrested on suspicion of murder.
Det Ch Supt David Sandall has told Kayleigh's family to prepare themselves for the worst
Det Ch Supt David Sandall said: "Since we started looking for her we have found her mobile phone in Melbourne Road, Ibstock and items of clothing which we believe are hers in the Ibstock and Diseworth areas.
"In all the circumstances, we fear the worst and have told her family to prepare themselves that we are now treating her disappearance as a murder enquiry.
"We have become increasingly concerned for Kayleigh's safety as the hours have passed since she was dropped off by her dad on Friday evening.
"Five days on, we've heard nothing from her, and this is completely out of character."
Around 20 police officers search a field off Ashby Road, in Belton, Leicestershire, and a plot of land near a lay-by has been cordoned off
Leicestershire Police has searched several locations including Sence Valley Forest Park, Ibstock and a field off Ashby Road, in Belton, Leicestershire.
Mr Sandall said: "The park has been cordoned off and is likely to remain so for some days yet while we conduct a thorough search of the area looking for her.
"A number of other locations are currently being searched, including an area in Belton and Diseworth."
The two men were arrested on Monday on suspicion of kidnap and have now been re-arrested on suspicion of murder.
They remain in police custody for further questioning.
Mr Sandall has urged anyone who was in the Diseworth or Belton areas between Saturday afternoon and Monday morning to contact them.
Friday 13 November
Kayleigh is dropped off at 18:00 GMT by her family outside Ibstock Community College to spend an evening with friends.
Saturday 14 November
Kayleigh contacts her family on Saturday morning, according to police.
Det Ch Supt David Sandall says: "We have been trying to piece together her last movements and we believe she may have been in the Sence Valley Forest Park area on Saturday afternoon."
Monday 16 November
Two men, aged 27 and 28, are arrested in connection with Kayleigh's disappearance on suspicion of kidnap. Police made the arrests in the early hours of Monday morning.
Police cordon off a house in Baker's Croft and make an urgent appeal for witnesses as they grow increasingly concerned over Kayleigh's disappearance.
Tuesday 17 November
The entrance to Sence Valley Forest Park is cordoned off. A forensic tent is erected and a tactical support team is brought in.
Police say Kayleigh's phone has been found by a member of the public.
Kayleigh's parents, Stephanie Haywood and Martin Whitby, make an appeal in the hope of finding their daughter.
Police are given a further 36 hours to hold and question the two men arrested.
Wednesday 18 November
The search of Sence Valley Forest Park resumes.
Police activity moves to the Belton area, less than 10 miles away from the park. A tent had been erected in the Belton area.
At 13:00, police announce they are treating Kayleigh's disappearance as murder, and the two men have been rearrested on suspicion of murder.
Cordons remain in place at the park and the search is widened to other areas including Belton and Diseworth.