A youth who went to steal mobile phones killed an Indonesian origin woman and her three children after he was identified by the victims, said police.
The victims are Smrity Fatema, wife of a Bangladeshi expat named Kajol Miah, their daughters Sabrina Sultana Noora, 16, and Haorin Hawa, 12, and their speech impaired son Fadil, 8.
The thief, Parvez, 17, hacked them and made sure they were dead by slitting their throats. He also raped the two daughters before killing them.
Parvez, a resident of Sreepur, gave his confessional statement to the police on Monday, saying that he committed the murders on his own.
A team of the Police Bureau of Investigation (PBI) arrested Pervez, a neighbour of the victims, from the Abdar area based on a tip off, Additional Police Superintendent Nasir Ahmed Shikder, in-charge of CID and PBI of Gazipur unit said at a press briefing on Monday.
Police seized Parvez's blood stained clothes and stolen mobile phones and ornaments from his possession.
Kajol's father Abul Hossain filed a case against the unknown murderer on Friday.
Kajol Miah, a resident of Gafargaon upazila in Mymensingh, is currently working in Malaysia, and his wife and children lived in their two-storey home at Telihati union, said Kajol's elder brother Arif.
On Wednesday evening, Fatima asked Arif to buy her some essentials from the market.
Arif, while going to the market the next morning, called out from outside Fatima's house, but getting no reply, he left thinking that everybody was asleep.
Around noon when Arif left home to go to the market again, he went to Fatima's home and called out again. Getting no response, he climbed a ladder, which he found on the back of Fatima's house, to the second floor and found the back door of the floor open.
He entered the floor and found the bodies of Fatima and her children with their throats slit.
He also found that the bodies had no clothes on them.