18 November 2015 Last updated at 15:00 GMT
Det Ch Supt David Sandall said it was proving an "extremely traumatic time for her parents" and they are now treating the disappearance of the 15-year-old, from Measham, as murder.
The teenager has not been seen since about 18:00 GMT on Friday when she was dropped off outside Ibstock Community College.
Two men, aged 27 and 28, who were arrested on Monday on suspicion of kidnap have been re-arrested on suspicion of murder.
More updates on this and other stories from Leicestershire.

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Craig Cathcart put the visitors ahead before substitute Simon Church won and scored an 89th-minute penalty.
"There were lots of positives out of it even if we'd have come off and lost 1-0. They had a good mentality and attitude," said Coleman.
Wales face another Euro 2016 warm-up game against Ukraine in Kiev on Monday.
"We look forward to our next challenge now," added Coleman.
"The team will change up again, and we'll see how they go again."
Striker Church, currently on loan at Scottish Premiership side Aberdeen from Reading, was delighted with his equaliser from the spot.
"Northern Ireland were a tough side to play against. They've obviously done well to get where they are and it was a tough game," he said.
"We wanted to do well because it was the last time a Wales crowd would see us before the Euros and we wanted to put in a good performance.
"I've just got to keep going now and hopefully score some goals. This is a great squad to be part of."

The adult female's remains - including a head and hands found in a bag - were discovered in eight locations, Irish police have confirmed.
They are investigating whether the death is linked to a personal dispute.
More than 200 gardaÃ­ (police), Irish soldiers and civil defence personnel are continuing to search the area.
The man arrested remains in police custody in Bray, 20km (12 miles) south of Dublin, where he can be questioned for up to 24 hours.
He presented himself to GardaÃ­ in County Wexford on Tuesday night and was subsequently arrested, Irish broadcaster RTE reported.
The focus of the murder investigation changed following a series of developments on Tuesday evening.
The results of DNA tests from the partial torso discovered by two walkers in the undergrowth, close to Military Road, on Saturday night showed the body was that of a woman.
More human remains, including a head and hands, were discovered over a 30km-area on Tuesday.
Police said they had now recovered most of the remains, and that there is only one victim.
Supt Pat Ward, described the unprecedented case as "troubling".
"We are conscious of the fact that the body found is that of a loved one," he said.
"What we have found are limbs, we've also found some significant parts of the torso and we've also found in one of the locations, in a bag, the head and the hands of the deceased," he added.
The police officer leading the search for missing Leicestershire teenager Kayleigh Haywood has told her family to prepare themselves for the worst.
[NEXT_CONCEPT]
Wales manager Chris Coleman said he was pleased with his team's performance after they came from behind to draw 1-1 with Northern Ireland in Cardiff.
[NEXT_CONCEPT]
A 32-year-old man is being questioned in connection with the murder of a woman whose body was cut up and dispersed in the Wicklow Mountains.