The Standard has established that the missing piece of evidence lies between the point where he disembarked from a bodaboda and the point where his body was found the next morning a hundred metres apart.
The team has also managed to trace Dr Langat's last movements from at least two entertainment joints where he is said to have taken various alcoholic drinks before trekking back to the hospital.
Police sources revealed that Dr Langat was in the company of his four peers. The four began their evening at a keg joint opposite the hospital's administration at around 6 pm on Friday.
According to CCTV footage, which The Standard has obtained, Dr Langat is seen in the company of two other friends, also medical interns, at Havana Lounge in London Estate at midnight.
At 12:08 am Saturday, Dr Langat gets up from his seat while scrolling on his phone. He appears to bid his friends goodbye, but they appear to pull him back to stay longer.
He manages to convince them and leaves the club while staggering at 12:09 am.
Sources privy to the investigations indicate that he trekked towards Nakuru ASK Showground after he failed to reach an agreement with a bodaboda rider on how much he was to pay.
At ASK Showground Junction, CCTV footage shows him walking at 12:21 am.
He then walks to the Royal House Liquor shop, which had already closed. Langat engaged with the guard on duty, Emmanuel Cheruiyot, who has since recorded a statement with the DCI.
The Standard traced Mr Cheruiyot, who described Langat as a stranger who revealed he was heading to the hospital.
"In his drunken stupor, he approached and told me where he was headed. I advised him to take a bodaboda and warned him against walking since streetlights on that road are faulty and it was dark," said Cheruiyot.
At 12:24 am, Langat walked back to the road where he was seen staggering for a minute before heading back to the closed liquor shop.
A minute later, he hails a bodaboda rider who stops and agrees to drop him at his destination.
He struggles and manages to board the bodaboda, which takes off and leaves the camera's view at 12:26 am. This is the last time Langat has been traced while still alive.
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When his body was discovered on Saturday morning, the detectives found his mobile phone still intact in his pocket.
Through the device, the police managed to trace the bodaboda rider, who has been identified as Dominic Yego.
Data from the phone indicate that Langat paid Yego Sh100 for the ride at exactly 12:30 am.
In his statement with the police, Yego told detectives that the doctor requested to be dropped at a junction within the hospital.
Langat was to walk the remaining part of the journey to staff quarters, a few metres away.
"It is a distance of 100m from where he was dropped to where his body was found. What happened in between is yet to be established. Unfortunately, the hospital CCTVs were not functional," said Mr Kamau.