The couple was found dead at their home in Kiambu town after a massacre.
Jonathan Mukundi Gachunga , 42-year-old, body was found along with that of his wife Phelomena Njeri, 30 hours after the incident.
The cause of the incident is still unknown. Friends who had seen Gachunga hours earlier said he looked happy.
Gachunga had a firearm license and ran his spare parts store in an industrial area in Nairobi. His wife worked in a store.
He allegedly shot his wife three times Tuesday night before turning the gun.
The lifeless bodies of the two were found in their locker room. They were then transferred to a morgue.
Police said they found his small pistol from the scene. Kiambu police chief Ali Nuno said they were investigating the case.
He adds the number of suicides in recent days, which has reached nearly 600 in four months.
On July 31, a prison guard committed suicide at his home in Kamagambo area, Migori County, days after taking social media and threatening to do so.
The body of Constable Seth Ojwang, 33, was found hanging from his roof. He was imprisoned in the Siaya prisons.
Ojwang had threatened to kill himself last week because of domestic problems he and his wife were having.
Her family told police that they knew the deceased had a problem with the woman and that they knew it was the cause of the incident.
Police say there have been a large number of suicide cases between civilians and uniformed officers, which is alarming.
A report from the Directorate of Criminal Investigation shows that at least 500 people have committed suicide in separate cases in three months (March-June) in the country.
The report adds that about 409 people were seriously assaulted during the same period, between March and June.