Parvez Hossain alias Sumon, 22, was detained around 10pm on Monday.
RAB 4 Savar CPC Camp Commander Major Mohammad Masisur Rahman told the Dhaka Tribune: “Sumon had been staying at a house in Gabtoli for a few days.”
“On information, we picked him up when he came out of the house last night [Monday].”
The RAB official said: “In the primary interrogation, Sumon confessed his involvement with the murder.”
He said Sumon used to stalk Billal's daughter Shabnur for long.
“Billal was found dead on November 2 after he complained to Sumon's father about the matter” he added.
Confirming the matter, RAB Media and Legal Wing Senior Assistant Director ASP Mizanur Rahman Bhuiyan said: “Details regarding the matter will be disclosed in a press briefing to be held at RAB 4 headquarters in Mirpur around 11am on Tuesday.”