Neeraj Gupta was hit on the head with a brick by the man, stabbed thrice, police said.
A 46-year-old businessman, who was in an extramarital relationship with an employee, was stabbed to death allegedly by the fiance of the woman who then stuffed the body in a suitcase, boarded a train and disposed it in Gujarat's Bharuch, police said on Wednesday.
A quarrel had broken out at the woman's rented house in northwest Delhi involving her, her fiance and her mother, and victim Neeraj Gupta, a resident of Model Town, after he objected to the wedding, they said, adding the incident took place on November 13.
The police said Mr Gupta was hit on the head with a brick by the man, stabbed thrice in the stomach, and later, his throat was slit. The woman and her mother helped him in disposing the body, they added.
All three accused -- Faisal (29), her mother Shaheen Naaz (45) and fiance Juber (28) -- have been arrested, police official Vijayanta Arya said.
The matter came to notice after police were informed that Mr Gupta had gone missing from northwest Delhi's Adarsh Nagar.
Neeraj Gupta's wife told police that she suspected Faisal to be behind her husband's disappearance. She also disclosed that Faisal and Neeraj Gupta were in a long-standing relationship, a senior officer said.
Based on her complaint, a case was registered under section 365 (Kidnapping or abducting with intent secretly and wrongfully to confine person) of the Indian Penal Code and Faisal was interrogated, the police said.
"During the interrogation, Faisal disclosed that she worked for Gupta and was in an extramarital affair with him for the last 10 years. Her parents wanted to get her married to Juber and she got engaged to him. When she told this to Gupta, he discouraged her from marrying anyone and came to her rented house in Kewal Park extension in the area of Adarsh Nagar where heated arguments ensued between him and Juber, Faisal and her mother," the official said.
During the altercation, Gupta pushed Faisal which enraged Juber and he attacked and killed him, she said.
After killing Mr Gupta, they stuffed the body in a suitcase and reached Nizamuddin railway station in a cab. Juber, who works in the pantry of Railways, boarded the Rajdhani Express with the suitcase and disposed the body near Bharuch in Gujarat, the official said.
The knife and the brick used in the crime have been recovered, the police said, adding efforts to recover the body are being made and further investigation is in progress.