The Detective Branch of Dhaka Metropolitan Police came up with the findings at a press conference on Thursday.
Police recovered the bodies of Rahima Begum, 60, and “housemaid” Sumi Akter, 20, at the House No. 9 on Road No. 2 of Block A in Mirpur-2 on Tuesday evening on being called by locals.
Rahima was running the sex trade with the help of one “Babul” as a tenant while Sumi joined the work on Monday, police said.
DB spokesman Abdul Baten said both had admitted to strangling Rahima and Sumi.
The duo went to the house on Monday to spend the night there, but they had the money for only one client, Baten said.
One of them spent the night with Sumi while the other stayed on a veranda and the duo killed the women later fearing that Babul would kill them for paying less, the DB spokesman said.
Police would seek permission from court to grill the suspects in custody for more details, he added.