Wechuli, a traditional healer who lived in Kawangware, Nairobi, went home with his girlfriend of four months, Jane Kadogo Mutiso.
Sometime after they had retired to bed, Wechuli who lived with his two children, called his daughter and asked her to bring him a knife.
Moments later, the neighbour's daughter heard the healer telling someone to kneel down and ask for forgiveness.
The two were naked, and the guy was telling the woman to close her eyes as the daughter peered through a crack in the door, overcome with curiosity.
At the time, he was wielding a knife.
When they spotted the guy and his two children without the woman, the girl immediately ran over to her mother and described what she had witnessed.
Mother and daughter went back peeping in response to this, and when they used a torch they discovered a leg.
They contacted the watchman, who then contacted the landlord's son, who unlocked Wechuli's home by calling the watchman.
They were astonished to discover a woman's decapitated, naked body inside. Kadogo's stomach was cut, exposing her intestines.
A knife was located close to the body.
When they saw this, the witnesses went to the Muthangari police station and reported the event.
When the police arrived, they discovered Kadogo's head had been put in a basket. A calabash contained additional ceremonial supplies including a feather, twigs, and sorghum sticks.
The bleeding knife was set down next to the victim.
A autopsy revealed that lesions to the neck and abdomen from blunt force trauma were the cause of death. The corpse and head matched Kadogo's, according to the DNA study.
Wechuli later showed up at the police station and was detained there.
He was sent to the Mathari Hospital for a mental evaluation after being taken to the Kabete Police Station.
The man's mental state was determined to be normal by the doctor, and the trial got underway with the prosecution calling 11 witnesses.
When pressed, Wechuli argued that he had no desire to murder his partner.
Kadogo urged they continue making love despite his claims that he felt dizzy and exhausted during that time.
When he laid on her chest in response to agony, the woman's voice started to sound like an epileptic.
The High Court was informed that Wechuli then noticed a large hand approaching him and that he used a large knife that he was holding to chop it.
When he looked down, he saw a vision of a headless body before the head appeared. He then saw himself in a desert with a corrugated house and light.
Wechuli claimed he observed the man holding a head in his hand before throwing it, gathering his children, and directing them to their mother's home in Kibera.
He stated that he was queasy and could smell alcohol on the way to the bus station.
Wechuli returned home after leaving his kids off to see a gathering and a woman yelling, "The grandfather has killed someone."
Wechuli continued by saying that he had mental health issues about 1986, but he had traditional medicine used to treat and cure him.
"According to him, if he was in his right mind, he would not have murdered the deceased. He pleaded that he had no intention of committing the offence," court documents read.
The trial court determined that the overall picture painted by the circumstances was one of a guy who understood exactly what he was doing and that his purpose to cause death was extremely clear.
Additionally, he had not proven his lunacy.
The court found him guilty on March 8 and gave him the death penalty.
Wechuli filed a petition with the Court of Appeal, claiming that the trial judge committed a legal error by neglecting to take into account his mental state at the time of the offence.
The prosecution requested that Wechuli undergo a second examination, which was approved, the court discovered after analysing the matter.
After hearing his father claim that his son had a mental disorder when he was 12 years old, this occurred.
But the mental testing never happened.
The accused person must establish that he was strictly of unsound mind at the time the offence was done in order for the defence of insanity to be accepted.
After reviewing the events leading up to Kadogo's murder, appellate justices Asike-Makhandia, Agnes Murgor, and Ngenye-Macharia came to the conclusion that the murderer was sane.
"The appellant was still cognizant and conscious enough to know what he was doing and that it was wrong. His actions after beheading the deceased betray him all the more," they said.
"The insinuation that he suffered from a mental illness when he was 12 years old remains nothing more than a mere unsubstantiated statement."
The judges held that Wechuli was mentally fit when he killed his girlfriend and dismissed his plea.
The appellate court found that the prosecution had proved its case beyond reasonable doubt and upheld the trial court's decision.
"Accordingly, there is no basis to warrant our interference with the sentence meted by the trial court. In the upshot, we find that the appellant’s appeal is without merit and the same is hereby dismissed in its entirety," the judgement delivered on September 22, reads.