A 23-year-old youth from Outer Delhi was arrested on Wednesday for killing a man who he alleged had an extramarital affair with his mother,the police said. The suspects mother,Sunita Devi,38,was also arrested on charges of being an accomplice to the murder. The police,after initial interrogation of the mother-son duo,said the youth,identified as Naveen,killed Anil Kumar on August 19 after he found him in a compromising position with his mother at their house in Bahadurgarh. Kumars body was found near Bawana canal in Outer Delhis Samaipur Badli on August 20. The police traced Kumars residence to Badli Extension through his driving licence. After finding out that Kumar had an affair with Sunita Devi,the police went to the latters house and found Sunita and Naveen absconding. Sunita was finally traced to another house at Bahadurgarh on Tuesday,a senior officer said. She initially tried to mislead the police during interrogation but divulged details of the murder on sustained interrogation, the officer said. Anil Kumar had gone to Sunitas house in Bahadurgarh on August 18 Sunita had reportedly called him. The officer said her son Naveen came to the house sometime during the night and found his mother and Kumar in a compromising position. Enraged,Naveen allegedly beat up Kumar and smashed his head against the wall Kumar succumbed to injuries in the early hours of August 19,the officer said. Sunita and Naveen then put Kumars body in his Santro car and dumped it near Agra canal that night,according to the officer. The police said Sunitas husband Karamvir Singh,a TB patient,lives separately with his brother in Badlia village. The couples elder son is mentally disturbed,the officer said.