A telecommunications expert traced the movements of a radio believed to have been used by one of the four Administration Police officers charged with killing three people.
Mr Kennedy Mwadime said he was asked to trace the movements of nine police radios.
The detective said the signal was captured at Syokimau AP post on June 23, 2016 around 12.20pm.
The prosecution said it was the time Mr Willie Kimani, Mr Josephat Mwenda and taxi driver Joseph Muiruri were abducted after leaving Mavoko law courts. Mr Kimani was a lawyer.
AP officers Fredrick Leliman, Leonard Maina, Stephen Cheburet, Silvia Wanjiku and an informer Peter Ngugi have denied killing the three.
The signal was at the post for about 20 minutes. Later in the evening, the signal was captured near Mlolongo police station, then at Syokimau police station three hours later.
Mr Mwadime said the signal was then traced to a field in Soweto between 8.40 and 9pm.
Some minutes to midnight, the signal was on the Eastern bypass and later Thika Road.
According to the prosecution, the three were abducted and held at the AP post for some hours before being taken to the field where they were tortured and killed.
While being led in his testimony by the prosecution, Mr Mwadime said it was difficult to tell the officer holding the gadget but with a system audit, the officer could be traced.
The bodies of the men were retrieved from River Athi a week later.
Mr Kimani was representing Mr Mwenda in a complaint he had made against Mr Leliman at the Independent Policing Oversight Authority.
The hearing was adjourned to November 12.