Police on Friday evening arrested a 27-year-old suspect believed to have information on the death of The Star journalist.
The suspect, Franklin Lutta, is the brother to Victor Lutta who is also a suspect in the case.
He was arrested at Mutumbu area in Gem, Siaya County.
Franklin is currently being held at Ugunja Police Station where he is helping the police with the investigation into the murder case which was reported on Thursday morning.
"I cannot give much details right now. However, I confirm that we arrested the fifth suspect around 6 pm. I will give more information as the investigations over the case continue," County Commander Francis Kooli said.
His arrest brings the total number of suspects in police custody to five.
The four suspects who had been initially arrested include; Chief Inspector of Police Sabina Kerubo, Victor Lutta, a house help called Joyce Awuor together with her daughter. The four are alleged to have been in a house where Oloo was killed.
According to the relatives of the late journalist, the body of Eric Oloo is currently at the morgue in Sega, Ugenya Sub-County. The postmortem test will be conducted on Monday next week.
Oloo's death was reported to the police by a landlord of the apartment where the deceased together with Kerubo had been living for a period of 14 months.