The police are also yet to determine if Njuguna and Chege participated in the murder of Ndunge.
The murder incident happened on Monday, April 17 and the man stayed with the body in the house stuffed it in a suitcase and later in a sack before he left it at the scene it was found by neighbours.
Njuguna also informed the officers that the two were working in a hotel within Kamakis where the deceased was a cashier and the suspect was a chef.
He informed officers that they had a domestic quarrel where the suspect hit the deceased on the head and killed her instantly.
When he realized she had died, he decided to find ways of disposing of the body.
The suspect then put the body of the deceased in a suitcase that was in the house.
The suspect also led the officers to Mukuyu area in Muranga where they also recovered the mobile handset of the deceased from his cousin.
The mobile phone was recovered on Friday as part of the evidence.
Ruiru head of DCI Justus Ombati termed the developments as a breakthrough in the murder probe.
The incident was discovered by residents who noticed the suitcase placed at the entrance of the residence.
Police said they were called to the scene and informed of the discovery before picking it to the mortuary.
The police asked for a bed sheet from one of the tenants there to cover the badly mutilated body as they processed the scene.
On checking they realized the woman had an injury on the head and was half naked.
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