Shiko, who served as the collation agent for PDP in Kaduna south local government of Kaduna state, made the claim at the tribunal on Thursday.
He said the results were doctored in his presence.
PDP and Atiku Abubakar, its presidential candidate, are challenging the victory of Buhari in the February 23, 2019 presidential election.
Serving as the 20th petitioners’ witness, Shiko said the election in his area was marred by over-voting and allocation of figures to parties.
Under cross-examination by Charles Edosomwan, counsel of the All Progressives Congress (APC), he said his account of irregularities during the election in his area was based on the reports he received from polling units agents and those he personally witnessed.
“My statement was based on the reports I received from the polling unit agents and what I saw on the result sheets which were forwarded to the local government collation centre,” he said.
“There were cases of overvoting, and allocation of figures. These were what were carried to the Local Government collation centre. In my presence, the results were doctored.”
While responding to questions from Yunus Usman, counsel of the Independent National Electoral Commission (INEC), Shiko said “figures were wrongly credited to the APC.”
“At the collation centre, I made complaints when the results were announced and I protested by refusing to append my signature to the result sheets,” he said.