DETECTIVES are examining closed-circuit television camera (CCTV) tapes in the hope they will reveal the killer of shop assistant Jenny Nicholl.

A team of officers is reviewing hundreds of hours of footage from cameras in Carlisle, in Cumbria, and Jedburgh, in the Scottish Borders.

The move comes after police revealed text messages were sent from both places on the 19-year-old's mobile phone after she disappeared.

It is believed the texts were an attempt by the killer to throw police off the scent.

Tapes have been seized from town centre CCTV systems and petrol stations on the outskirts of the towns.

Detective Inspector Pete Martin, who is leading the investigation, believes Miss Nicholl, from Richmond, North Yorkshire, knew her killer.

He said yesterday: "We're examining a lot of CCTV images from Jedburgh and Carlisle for sightings of Jenny's associates, or her associates' vehicles. Jedburgh in particular has a very good town centre CCTV system."

Police investigations in the two towns failed to produced any evidence the teenager visited the areas.

Texts were sent to several of Miss Nicholl's close friends from Carlisle at about noon on Saturday, July 9 - ten days after her disappearance.

Another message was sent to her father, Brian, at about noon on Thursday, July 14, from the Jedburgh area.

The messages included information that would only be known by someone who knew Miss Nicholl.

Police say mechanical problems with her car and details of her friends were included.

"These text messages were clearly intended to give the impression that Jenny was safe and well," DI Martin said.

"Police inquiries were launched in those two areas, enlisting the help of the local forces, the local media and with North Yorkshire officers being sent to the Lake District and Scotland.

"However, despite these inquiries and other detailed investigations nothing was found to indicate that Jenny is still alive."

Officers are still following up fresh leads received after police announced last week the investigation had become a murder inquiry.

Miss Nicholl was last seen by her parents at the family home on June 30.

She was reported missing on July 4 when she failed to turn up for work at the Co-op supermarket, in Richmond.

Her car was found abandoned at the Holly Hill pub, on the outskirts of Richmond, the same day.

Officers have spent the week searching woodland about a mile from the pub for Miss Nicholl's body.

It is understood the teenager would camp in the area with friends.

Anyone with information is asked to call (01423) 539334.