32-year-old Mohammad Khursheed had stabbed to death his sister-in-law Afsana Khatoon in Madhubani area of Bihar on April 25 and escaped to Nepal.
He was arrested yesterday when he returned from Nepal when he came to Delhi to meet his wife and children, Crime Branch of Delhi Police said.
Afsana developed illicit relationship with Khursheed's elder brother Mohammad Hakim after the death of her husband and Khursheed's younger brother Mohammad Nazir. She was pressurising Hakim to divorce his wife and disown his sons and marry her. When Khursheed came to know about this, he hatched a plan to murder her, a senior police officer said.