Police on Friday recovered the throat-slit body of a teenage boy from a litchi orchard in Thakurgaon Sadar upazila.
The deceased, Antar Islam, 18, a pick-up van driver, was son of Nur Islam and used to live at his maternal uncle's house at Munshipara village in the upazila.
Meanwhile, following a case filed by deceased's mother Afroza Begum with Sadar Police Station, police detained Antar's aunt Lutfa Begum, 29, her alleged boyfriend Rafiqul Islam, 47, and driving instructor Mohammad Shaheen.
According to the case statement, Rafiqul and Lutfa had been in an illicit relationship for quite sometime. After Antar came to know the matter few weeks ago, Rafiqul decided to kill the boy and accordingly made a plan.
As per the plan, Rafiqul in cooperation with Shaheen phoned Antar and asked him to come to the orchard on Thursday evening.
When Antar reached the orchard the duo took him tactfully inside the orchard and killed him there at night.
Police said they are interrogating the arrestees to find out the motive behind the murder.