MADISON, Wis. -- Madison police have updated their description for a person of interest sought in connection to the fatal stabbing of a Madison man near Park Street earlier this week.

The 31-year-old victim, Joel Marino, was found unresponsive in an alley just off the 700 block of South Park Street, near West Shore Drive, on Monday afternoon. Authorities said Marino died from stab wounds and that they are treating his death as a homicide.

As part of the investigation into Marino's death, detectives said that they are looking for a man who was seen in the area at the time of the killing. The person of interest is described as a white man with a thin build and about 6 feet to 6 feet 1 inch tall. He was last seen wearing a white stocking cap with a red "W" on the front and a tan, sheepskin-type jacket and was carrying a gray backpack, which appeared to be new.

Investigators said on Wednesday that they recovered the hat and backpack, which they believe were worn by the person of interest. Authorities released a photo of a jacket similar to the one worn by the man. Police said it's unclear whether the actual jacket worn by the person of interest has a hood.

Police said that detectives are continuing to investigate, and items including the recovered hat and backpack are being taken to the Wisconsin State Crime Lab for forensic tests.

Authorities said that they're hoping residents living near the scene can help investigators solve the case. Detectives said that they want to talk to anyone who may have been jogging or walking in the area about the time of the killing early Monday afternoon and saw anything.

The steps outside Marino's home, near Park Street and West Shore Drive, have become a make-shift memorial from family and friends.

On Thursday, police handed out about 70 posters to area businesses. Madison police Sgt. David McClurg said that he thinks disseminating information is vital.

"The more people that know about it, the more information that we get about suspicious things going on in the neighborhood, about something they may have seen, will ultimately lead to, hopefully, the solving of the crime," said McClurg.

Marino was a 1999 graduate of the University of Wisconsin-Whitewater with a degree in management computer systems. He was working as a representative for the medical device company.

A visitation for Marino will be held on Friday at Lake City Church at 4909 Buckeye Road from 3 p.m. to 6 p.m. The funeral will be at 2 p.m. on Saturday.

Marino's friends will be in the neighborhood on Sunday passing out fliers.

An anonymous donor has given $30,000 for a reward for information leading to a conviction in his death.

Police said that anyone with information on this case is urged to call Crime Stoppers at 608-266-6014.

Stay tuned to WISC-TV and Channel 3000 for continuing coverage.