Anti-Terror Police Unit (ATPU) at the rank of a Chief Inspector Monica Wambui Githaiga on Saturday collapsed and died at the Jomo Kenyatta International Airport (JKIA) minutes after arriving from Japan.
Ms Githaiga had gone to Japan for a short course and arrived at the airport after connecting through Dubai and Addis Ababa aboard Ethiopian Airlines.
It is reported that she had complained of feeling unwell while in Dubai, citing chest pains and dizziness, where she was treated and allowed to board her flight to Nairobi.
Upon arrival, according to witnesses quoted by the media, she collapsed and vomited before she was confirmed dead at a clinic at JKIA.
An autopsy is planned on the body to establish the cause of death.
Ms Githaiga was the lead investigator in the dusitD2 Hotel attack on 14 Riverside Drive, Nairobi on January 15 in which 21 people were killed.
In the investigation, Ms Githaiga unearthed that one of the suspects, Hassan Abdi Nur, received Kshh9 million from South Africa in three months and sent it to Somalia.
She also discovered that Nur had 52 M-Pesa agent accounts. Fourty seven were registered between October and December last year, each with a SIM card. He used different IDs to register the SIM cards.