Detectives investigating the murder of a man in Melbourne have revealed the victim had been shot a week ago.

Police say neighbours in Deer Park heard at least one gunshot last Tuesday morning, around 3am.

The man's body had been inside the home for a week and was only discovered yesterday afternoon around 4.30pm.

Police said the person who found the victim was not a family member, but was there for business related purposes.

Police at the scene today. (9NEWS)

Detectives are now appealing for witnesses and want to speak with anyone who witnessed suspicious behaviour in Erin Square last Tuesday morning.

Forensics combed the scene yesterday, and returned around 9.30 this morning.

Those who live in the street say the victim was a dressmaker with a Vietnamese background.

"He had a lot of people coming in and out. He used to do a lot of sewing," said Leo Henry.

Mr Henry said the man - whom he could not name - had lived in the street for five or six years, and was renting.