FEATURE: How dogged detective brought South Yorkshire murderer to justice - two decades after brutal attack
But there is more to this case than meets the eye.
It took the best part of two decades to bring a full murder charge against the killer.
Keeling assaulted his then lover Ann Robinson at their home in Truro Avenue, Wheatley, in December 2000. The brutal attack left her with brain damage and needing round-the-clock medical care.
He was jailed for attempted murder and then freed.
But Ann's health took a turn for the worse and she was admitted to hospital in 2014 where she died aged 58.
Due to the unusual nature of the case, it then took police three long years to finally bring a murder charge against Keeling - a full 17 years after his brutal attack on Ann.
Now, the dogged detective who was tasked with bringing Keeling to justice has revealed for the first time how he did it.
Detective Constable Ian Honeybone explained how this was the toughest case in his career to date.
He said: "You do sometimes read about cases where an individual has been assaulted and then died from their injuries some time later, but normally this is within a couple of years of the incident taking place.
“Yet here I was, faced with investigating the death of a woman who had been brutally attacked by her partner 14 years previously, suffering extensive and significant injuries that impacted the rest of her life.
“That’s practically unheard of."
After Ann's death in 2014 a post mortem concluded that she died from a chest infection.
But an inquest heard that this was linked to her immobility, which was in turn connected to the injuries Keeling had inflicted upon her.
The coroner noted the link between her injuries in 2000 and her death 14 years later and asked police to reopen the case.
This proved to be the catalyst for the investigation that eventually put Keeling back behind bars.
DC Honeybone said Ann’s injuries included "extensive internal bleeding from a puncture wound to her back, damage to her liver and abdomen, as well as catastrophic head injuries.
"She spent the remaining years of her life immobile, which must have been awful for both her and her loved ones."
The detective handed over his original case file to the Crown Prosecution Service and sought advice from a QC who concluded there could be a case to charge Keeling with murder.
DC Honeybone said: "But he wanted to be absolutely sure so we began the task of gathering more supporting evidence.
“So began an incredibly difficult task of contacting medical professionals that we thought may be able to help us prove beyond reasonable doubt that Ann’s injuries from Keeling were inextricably linked to her death so many years later."
He broadened the scope of his investigation and contacted Professor Charles Deakin, a renowned medical expert on criminal cases based at Southampton University.
DC Honeybone said: “We had to send him all of Ann’s medical records over the last 15 years or so, which as you can imagine, amounted to thousands of pages and Professor Deakin had to painstakingly review it all, to gain the best possible understanding of Ann’s health to help us determine what happened.
“From those thousands of documents, he produced an incredibly thorough medical report that concluded nothing else could have contributed to Ann’s death, nothing further had happened that could have caused her death, besides Keeling’s attack."
The matter was referred to the Attorney General - the chief legal adviser to the Government - who gave the go-ahead to charge Keeling with murder.
Keeling had already been found guilty of attempted murder and jailed for 14 years in 2001.
He served seven years of this sentence and after a brief period of freedom was brought back before Sheffield Crown Court on Thursday last week.
The 58-year-old, who later lived at Selby Road in Thorne, pleaded guilty to murder and was sentenced to life in prison with a minimum term of 18 years.
The time he previously served for attempted murder will be deducted from the new sentence, meaning he will in effect serve a minimum term of 11 years.
This brought to an end the most difficult case of DC Honeybone's career to date.
He said: "Even the judge remarked that this was an unusual case and it has certainly tested my abilities as a detective, but ultimately I’m just so pleased I was able to get answers for Ann’s family and some justice, even though it will never truly ease the pain of her loss.”