Businessman Chris Obure has been charged with the offense of failing to secure his firearm.
His bodyguard Robert Bodo was also separately charged with a count of being in possession of a firearm without a license.
They appeared before Magistrate Sinkiyian Tobiko on Friday and denied the charges.
They were released on a Sh50,000 cash bail each.
The case will be mentioned on September 30.
Obure and Bodo were charged on Wednesday with the murder of Kevin Omwenga.
The bail hearing for that case is scheduled for Monday next week.
The prosecution had opposed their release on bail and wanted them to remain in remand until the case is heard and determined.