At least six out of a total of 28 police officers killed while on duty in the country last year were shot by one suspect.
The 2015 Annual Crime Report also shows that 10 of the officers were killed in Nairobi.
A total of 102 other officers were injured while performing their duties, with 10 cases reported in Nairobi.
The Directorate of Criminal Investigations (DCI) attributed the shootings targeting police officers to Kennedy Mwangi, who was eventually shot dead on November 2, 2015.
Nairobi County DCI boss Nicholas Kamwende said Mwangi, who remained mysterious even in death, was only known by his alias, “Mwas”.
According to the police, between July 1 and November 2, 2015, the gang he led killed at least five officers and seriously injured three. He had also stolen at least five guns from the officers.
Mwangi, it is believed, killed the Administration Police (AP) officer in charge of operations in Njiru Sub-County, Chief Inspector Achilles Kiwanuka Imbachira, an Ruai on July 1, 2015, and stole his Ceska pistol and police radio. He then went underground and never used his phone again.
On October 29, 2015, he led a gang that killed Constable John Meme of Kasarani Police Station.
The incident occurred when Mr Meme and his colleague had responded to a distress call by boda boda riders.
Mwangi is also said to have shot and seriously injured two National Intelligence Service officers, a month later, about 150 metres from where Mr Meme was killed. He stole the officers’ two guns.
In another case, he is said to have killed Constable Johnson Muimi, who was attached to the Anti-Narcotics Unit.
He was shot at the gate of the Moi Forces Academy on Juja Road on September 26.
Mr Muimi had been driving along Juja Road at around 9pm when his car was rammed by a motorcycle.
He stopped to check the damage, but one of the two men on the motorcycle drew a pistol and shot him in the chest.
The gangster is also suspected of having been behind the shooting of Inspector Zadock Khamala, who was in charge of the Ngumo AP camp, on Kangundo Road, on May 18, 2015.
The gang is believed to have shot Constable Benson Karugu of the Anti-Terrorism Police Unit at Dandora Estate, on October 18. The Kisumu-based officer was in Nairobi on an assignment.
Police in Nairobi intensified the search for the gang leader, who was described as a smooth operator, but he continued to terrorise people.
Officers from the Flying Squad and Special Crime Prevention Unit eventually tracked him down to Maili Saba slum in Silanga within Dandora, and shot him dead.