Louise Evans, 48, died from stab wounds outside East Sutton Open Prison in Sutton Valence, near Maidstone, Kent, on Wednesday.
Police said murder inquiry detectives wanted to talk to a former boyfriend, Keith Prest, of no fixed address, whom she met about 18 months ago. Unemployed Mr Prest is 48, white, around 6ft 2in tall and of thin build.
Superintendent Steve Corbishley, a deputy area commander for Kent Police, said: "We urgently need to talk to Mr Prest and would appeal to him to contact us.
"If anyone has seen a man matching his description or photograph or knows of his whereabouts we would ask them to call us immediately by dialling 999 and asking for police or contact Kent Police on 01622 690690.
"I cannot stress enough that under no circumstances should Mr Prest be approached by anyone as he may present a danger to himself or others."
The body of Ms Evans, a single mother of two from Hothfield, near Ashford, who taught literacy to inmates, was found slumped behind her car in the car park by a colleague at about 5.15pm. She had left the jail at 4pm, police said.
"A post-mortem examination by a Home Office pathologist last night confirmed that Louise died from stab wounds," a spokesman said.
Police have set up a major incident room at Maidstone and have 20 officers working on the investigation.
East Sutton Park, a mansion house overlooking the Weald of Kent, first opened as a borstal in 1946. It holds both adult and young offender women in open conditions, preparing them for resettlement in the community, according to the Prison Service. It had an operational capacity of 100 as of last November, and is said to have an emphasis on resettlement with good community links.
Last Mod: 15 Eylül 2007, 17:39