Regional CID commander Musa Yego who confirmed the incident on Saturday said the officer was shot several times in Liboi border town by attackers while heading home from a local mosque.
"The attackers who were four in number hurriedly followed the officer on foot before opening fire on him and then escaped into the darkness of the night," Yego told Xinhua.
"The motive of the attack is not yet established, but the attackers are seemingly people who knew Mohamed Yerrow well, including the mosque he frequented for his evening prayer," Yego said.
Liboi is a small, but busy trading center, which is about 18 kilometers west of the Somali border town of Dobley, and 175 km east of Garissa town. Despite its proximity to the war-torn Somalia, it had rare incidents of insecurity for many years compared to more interior towns like Dadaab and Garissa.
Yego said the officer who has worked in Liboi for the last two years had not indicated or reported any threats to his life.
"We have deployed extra security personnel to seal off the border in a bid to apprehend the criminals who killed the officer and brought them to justice," Yego said.
He appealed to the members of the public at the border town to work closely with security officers, and volunteer vital information that could led to the arrest of the assailants who killed the officer or those planning to commit felony in the area.
"So far we have not yet made any arrest in relation to the killing but we hope to get them soon," Yego added.
Garissa County has suffered terror attacks targeting government officials, eateries, churches and security facilities since Kenya sent its troop for a peacekeeping mission to Somalia in 2011.