A sex offender has been jailed for fatally stabbing a forensic science student who dreamed of becoming a policewoman after befriending her on a canal towpath . David Marshall must serve a minimum of 20 years behind bars for the murder of Eni Mevish , a 20-year-old student at Staffordshire University . The 68-year-old stabbed her in the heart , lungs and liver six months after they met because he was 'jealous ' of her other friendships , Stafford Crown Court heard . The pensioner had already served a jail sentence for assaulting a 14-year-old girl when he stormed her house Stoke-on-Trent in November last year to butcher her with a kitchen knife . Eni Mevish was killed by a sex offender who stabbed her in the lungs , liver and heart six months after she befriended him while out jogging . The pair are thought to have met around six months earlier when Miss Mevish , originally from Manchester , was out jogging . Prosecutors told the court Miss Mevish had received financial support from the pensioner , though the nature of their friendship is not clear . On November 9 the 20-year-old received a number of text messages thought to have been from Marshall . While she was watching a film with fellow student Rizwan Bukhari , Marshall is understood to have arrived at her house drunk . He asked Mr Bukhari to leave them alone before being heard 'swearing , shouting ' and asking 'why did n't you text me ? ' The 22-year-old student then heard a 'slow scream ' and tried to intervene but was struck by the sex offender 's knife . David Marshall was on licence for sexually assaulting a 14-year-old girl when he killed Eni , a 20-year-old student . After Marshall had fled the scene he discovered Miss Mevish 's body in a pool of blood and phoned an ambulance . She had been stabbed in her heart , liver and lungs and died in hospital . Appearing via video link in Stafford Crown Court Marshall was told he must serve a minimum term of 20 years and six months for her killing . Sentencing , Judge John Wait said it was clear the sex offender had intended to hurt her . 'You came to be jealous of her friendships with fellow students and sought to distance her from them . 'It is clear you had in mind violence when you went to her home . ' The court heard how at the time of the attack Marshall was on licence for sexually assaulting a 14-year-old girl . 'At the time of this terrible offence you were on licence following a sentence for an offence of indecent assault , ' added Judge Wait . 'It was a condition of your licence that you notify your supervising ( probation ) officer of any developing friendship with a woman . 'It is noteworthy that you failed to tell your supervising officer of the relationship ( with Eni ) though you were asked on many occasions . ' In a statement released by police Miss Mevish was described as 'beautiful , clever and with her whole life ahead of her . ' 'Eni was a loving sister and daughter who was taken from us suddenly and violently . 'We are so proud of her achievements . We are devastated by her death . 'Nothing can make up for that but we are glad Marshall is now paying for his actions . ' The 20-year-old was studying to become a police woman at the time of her death . 'She would train really hard as she was so determined to join the police . 'Eni would run through the park and when she saw an officer she would say `` that ’ s what I want to be ’ '' - she just wanted to help , ' said close friend Melanie-Vanessa Enyong . The 20-year-old aspiring policewoman was in her second year of a degree in Policing and Criminal Investigation when she was murdered . 'She only ever wanted the best for people because she loved exercising so much she used to encourage us to get out there with her - that was the type of person she was . ' She is thought to have met Marshall while out running though details of their friendship are not known . One of her former lecturers said she was a 'warm-hearted and conscientious ' student . Speaking on behalf of Staffordshire University , Professor Andrew Jackson said : 'She is greatly missed by all who knew her . 'Today ’ s events bring that loss into sharp focus and our thoughts are particularly with her family at this very difficult time . ' She is thought to have met Marshall while out running though details of their friendship are not known . In the days after her death Thomas Barnes described how her housemate , Rizwan Bucari , had come into a shop to ask for help after seeing Marshall flee her body . 'She had blood pouring from a stab wound in her stomach , and cuts all up her arm . 'By the time the ambulance arrived , her breathing was very weak . I told them what had happened and moved so I did n't get in their way . 'It was surreal , after being in direct contact with that kind of situation it ’ s hard to concentrate on anything else . ' Marshall stormed the student 's shared house in Shelton , Stoke on Trent , ( street pictured above ) and killed her with a kitchen knife .
Eni Mevish , 20 , was stabbed to death by David Marshall , 68 , last November . The pair had become friends two months earlier while he was out jogging . He stabbed her at her home in the lungs , neck and heart with kitchen knife . Marshall , who previously abused a 14-year - old girl , admitted murder . He must spend at least 20 years behind bars before applying for parole .