A mentally-ill man 'taunted' a stricken Sheffield police officer as he repeatedly hit her with an axe, a court heard.
Nathan Sumner, aged 35, and of Plowright Close, Gleadless Valley, was in the middle of a psychotic episode when he carried out the horrifying attack on PC Lisa Bates on the evening of April 13 this year.
Sumner has pleaded guilty to inflicting grievous bodily harm but denies two other charges - one of attempted murder and an alternative count of causing GBH with intent.
Sam Green QC, prosecuting, said Sumner had been taunting PC Bates as he hit her with the axe, asking if she was going to kill him, and 'pausing to get the best angles to deliver his targeted assault'.
Sumner appeared in court in a suit and shirt, watching proceedings from the dock, for the first day of his trial, which is expected to last three weeks. Members of his family were in the public gallery.
Mr Green said: "On Wednesday April 13, Nathan Sumner attacked an on-duty police officer, PC Lisa Bates, with an axe in the Gleadless area of Sheffield.
"He chased her, then when he caught her, he struck her with the axe to the leg, head and hand.
"The flesh on the crown of her head was split open deeply and the index finger of her right hand was left hanging off.
"She suffered other injuries too, including a fractured skull. She required surgery.
"The prosecution say that, in setting about PC Bates in the way he did, as forcefully as he must have done to cause these injuries, with an axe, including forceful blows to her head, he must have intended to kill her and that was what he was attempting to do."
Mr Green said the trial will hear that Sumner had been acting 'oddly' in the days before the incident, 'going on about aliens and swinging an axe about' in the maisonette he shared with his girlfriend Kayleigh Barton.
He said: "You are likely to hear from her that the defendant has a history of using cannabis and alcohol and that in the few days before the attack on PC Bates, the defendant had been saying things like 'They're coming for me' and he had claimed to see demons in the corner of his computer screen looking at him."
Mr Green said that three days before the incident, Sumner had put his girlfriend up against a wall, punched and headbutted her, dropped her on her face and then pinned her to a bed while asking if her life was worth £100 to her father.
He said Sumner's 'strange and volatile behaviour' continued until the day of the incident on April 13, with Sumner starting to 'smash up' the living room using his axe.
The police were called by a neighbour in a flat below at about 7.30pm - resulting in PC Bates and her colleague PC Mark Garrett being sent to the scene.
Mr Green said Sumner, wearing only a pair of shorts, 'flew out' of his property and pinned PC Garrett up against a wall. This led PC Bates to attempt to use incapacitating spray on Sumner.
He said: "Whilst it had little effect upon the defendant, unhappily it had an incapacitating effect upon PC Garrett."
The defendant then ran back into his flat, returning with the axe.
Mr Green said: "PC Bates then ran, with PC Garrett in front of her as the defendant said words to the effect of 'Come on, I'm going to kill you'.
"She jumped to the bottom of the communal steps and at that point knew she had broken her leg in her attempt to escape."
Mr Green said witnesses described seeing Sumner repeatedly hitting PC Bates with an axe.
He said Sumner's girlfriend had run down to the flats beneath her in the moments before and told a neighbour named Simon Ellis that 'her boyfriend was in the process of killing two police officers'.
Mr Ellis allowed Ms Barton in his home and then saw PC Bates 'staggering' from the same staircase that Ms Barton had come down and fall forward towards the balcony railings.
Mr Green said Mr Ellis then saw Sumner follow her, lean over her and begin to hit her with a weapon in the thigh and head.
He said: "He was swinging the weapon repeatedly, despite PC Bates putting her hands up in an attempt to protect herself.
"The defendant taunted her as he set about her, asking if she was going to kill him and 'smash my head in'.
"He swing relentlessly, albeit pausing to get the best angles from which to deliver his targeted assault."
Another witness described seeing Sumner 'hitting PC Bates anywhere he could with an axe and just going at her constantly'.
Another police officer on duty that night described hearing PC Bates 'sounding petrified' on the police radio as he requested more back-up. As he headed towards Plowright Close, he heard a 'blood-curdling scream' over the radio which he believed to be PC Bates.
The court heard Mr Ellis ran towards the scene of the attack - leading Sumner to run off. Mr Ellis pulled the heavily-bleeding PC Bates into his flat, where he could see the index finger on her right hand was hanging off.
Mr Green said PC Bates suffered a large injury to the left side of her scalp, skull fractures, a fractured and dislocated left ankle that required surgery and an 'almost amputated' right index finger that also required surgery.
He said the severed finger was consistent with raising hands in self-defence.
Sumner had begun chasing after PC Garrett while wielding the axe, but dropped the weapon on a grass banking outside the block of maisonettes.
Sumner then went inside a nearby Co-op shop where he started shouting at staff and smashed a wine bottle and beer cans on the floor.
He told one worker 'I've cut two people's heads off with an axe and you are next Come here, come here'. The woman described him as 'slavering' when he made the comments.
When police officers arrived moments later, Mr Green said Sumner bit one officer in the arm and managed to grab a police baton off another as he was being restrained.
CCTV was shown to court of one officer appearing to kick Sumner in the back, prompting gasps from members of his family watching in the public gallery.
Moments later, Sumner was Tasered and fell to the ground before being handcuffed.
Mr Green said Sumner had been injured himself and while being taken to hospital for treatment, made threats to kill the officer he was with, saying he was going to 'chop your head off' once his handcuffs were removed.
He said he spat in the face of one officer and also attempted to wipe faeces in his face, as well as spitting at two other officers.
Mr Green told the jury: "In determining the defendant's state of mind at the time he injured PC Lisa Bates, you may wish to consider, amongst other factors, the defendant's violent, threatening, erratic and decidedly paranoid behaviour in the days before, the moments surrounding and after the attack, to assist you in gaining an insight into his state of mind."
David Brooke, defending, told the jury: "This is not an ordinary case. It is agreed on all sides that undoubtedly Nathan Sumner was suffering from a psychotic episode.
"He was mentally ill at the time."
CCTV was shown to the jury of an agitated Sumner wearing just blood-stained boxer shorts in the Co-op store before being Tasered by a police officer after grabbing a baton off another policeman.
Mr Brooke said prior to the altercation with the police in the shop, Sumner had been shouting 'Help me, they are coming for me'.
He said Sumner had been heard to add: "The aliens are coming for me, someone is trying to kill me. I'm the King of Sheffield, I will buy you a house if you help me."
A mobile phone video taken after Sumner had been arrested by a police officer was also shown to the jury of Sumner lying handcuffed on a blood-stained floor.
It appeared to show him saying to officers: "I have started off World War III. Get me an ambulance. In about 20 minutes, I'm going to die. This is my suicide mission.
"I'm the trigger, the mechanism. If I do it, you all die.
"You're starting World War Three. I'm going to go off in 30 minutes."
The case will resume on Monday.