Three women were arrested on Wednesday afternoon during a sting operation in the city suburb of Kinoo.
Officers from Anti Narcotics Unit and the Special Crime Prevention Unit seized 1.5 kgs of heroin and one sack containing approximately 5,000 rolls of marijuana.
The heroin was estimated to have a street value of over Ksh5.25 million.
Police claimed that the three suspects Rose Musanda, Anne Musanda and Mercy Musanda were the major controllers of the narcotics market in Westlands, Kangemi, Uthiru, Kinoo and Kikuyu areas.
The suspects were detained before being transferred to the JKIA court to answer to the charges.
In the same breath, the officers also reported that on Friday, they had intercepted a parcel from Scholastica Namunyu Imbiti which was destined to Mombasa via parcel service.
Tests from the package revealed that the parcel contained 350 grams of heroin with a street value of Ksh1.225 million.
This comes a few days after Mombasa court sentenced a Tanzanian man to 30 years behind bars and on top of that, slapped him with a Ksh 90 million fine which if he failed to pay would earn him five more years.
Hussein Masoud Eid had been arrested in 2018 with 10.2 kgs of heroin that was by then estimated to have a street value of Ksh30 million.
In a case that commenced in March 2018, Eid, together with two others, were charged after they were arrested at a hotel along Moi Avenue, Mombasa.