Police arrested a 35-year-old man on Sunday in connection with the killing of a 45-year-old man in suburban Goregaon in Mumbai last week, police said.
While Anil Mishra was arrested, the prime accused Amit Saurav is on the run, a police official said.
Police suspect that Mishra and Saurav attacked Nandlal Kanojiya, a resident of a chawl on October 31, after the latter scolded Saurav for urinating in front of his house.
While Kanojiya died on the spot due to stab wounds, his wife Urmila is in a critical condition.
Mishra was arrested from Shashtri Nagar locality in suburban Andheri on a tip-off.
Malad police station senior inspector George Fernandes said further investigation is underway.
A chawl is the type of a residential building comprising small rooms with a particular layout.