The punishment was handed out by the International Association of Athletics Federations, the sport's governing body, in February after Mwangi was accused of seeking bribes to reduce the doping bans of two athletes.
His provisional suspension came after former AK president Isaiah Kiplagat, ex-deputy David Okeyo and former treasurer Joseph Kinyua were banned by the Ethics Committee on charges of mis-using funds from a sponsorship by U.S. sports manufacturer Nike.
All the officials deny any wrong-doing.
Joy Sakari and Francisca Koki Manunga said Mwangi asked each of them for $24,000 to reduce four-year bans.
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Sharad Rao, Kenya's barrister appointed by the IAAF, said on Friday that he would complete his probe into the affair by mid-May.
"I am aware of the IAAF Ethics Committee declining his appeal so I am formally taking over investigations," Rao added.
Mwangi told Reuters that he wanted any hearing to be held in public.
"My legal team appealed against the six-month suspension because we thought it was too long and punitive given that I was an employee and not an elected member of the board like the others," said Mwangi.
"Now that our appeal is not successful we are looking forward to a fair and open hearing. I maintain my innocence, hence we want the hearing conducted in public because I want to face our accusers."
Kenya is a global leader in endurance running on the track and in city marathons but more than 40 of their athletes have been banned for doping in the past three years.
(Editing by Tony Jimenez)
