The Kenya Pipeline Company has lost an unknown amount of fuel believed to be worth tens of millions of shillings through a sophisticated siphoning racket.
The criminals dug a 20-metre tunnel through granite rock to access the main pressurised pipeline, which they punctured and then inserted a valve to regulate the flow of stolen fuel.
The fuel then flows through a hose pipe into a fenced, desolate compound, from where tankers are loaded with the fuel. There is only one iron-sheet shelter in the compound.
The racket was busted when Directorate of Criminal Investigations (DCI) officers, together with KPC engineers, acting on a tip-off, arrested two people on Tuesday night at Kathangaita in Mlolongo township in Mavoko, Machakos County.
Another suspect was later apprehended. The three include two workers at the site, and a tanker owner.
It has not yet been established how long the illegal "depot" has been operating, but it is notable that the drilling was not reported earlier, despite there being clear evidence of the rock being blasted using explosives.
The tunnel is about one metre in diameter. An electric cable is inserted through it to power the bulbs that lit the way for the criminals as they made their way to turn the valve on and off.
"There's no way you can do this unless you have the technical know-how or work for a pipeline. Not with this kind of pressure," Interior Cabinet Secretary Fred Matiang'i said when he visited the site yesterday, accompanied by Inspector General of Police Hillary Mutyambai.
Dr Matiang'i ordered the DCI to carry out a thorough investigation into the racket and report to him.
"We must bring this to an end. This must be a racket. Ordinary criminals cannot do this," he said.
During the arrests on Tuesday night, one suspect escaped and is yet to be tracked down.
It is believed he could have disappeared into the tunnel, which the investigators are still wary of entering yet because of the strong petrol fumes.
The intricate work was exposed after KPC excavated the site. It has since been sealed off as a scene of crime.
The suspects were taken to court on Thursday and the DCI expects to make more arrests.
Dr Matiang'i took a KPC manager, Mr George Ajowi, to task over the scam, wondering how such a thing could go on undetected.
Meanwhile, Mr Mutyambai ordered the County Police Commandant to expedite the investigations.
"We have to get these criminals," he said and ordered his officers to investigate how power was connected to the compound. In the lone shelter was a bed and some clothing.
Area residents said they were not aware of the illegal activity, although they said they would see fuel tankers driving in and out of the compound.
Recently, KPC has been reported to be losing fuel through spillage.
Last September, the company recalled more than 170,000 litres of super petrol loaded at its Kisumu depot after it was found to be mixed with water.