The year 2010 is coming to a bitter end for one Calgary family whose son was slain earlier this year with no charges laid at this point.

Family members of Mark Mariani say the holiday season was difficult.

The 47-year-old was beaten to death nearly three months ago and no one has been charged in his murder.

"The minute you start talking about Mark, tears come to your eyes," said his father Norbert Mariani.

"He used to lay down by the coffee table and watch TV and I'd be sitting in my chair and now you miss him."

Mark's body was discovered Oct. 3 in a parking lot on 16 Avenue N.W. Police believe he was assaulted in an alley and then staggered to his vehicle in the parking lot where he collapsed and died.

Investigators believe the attack may have been random.

Norbert said his son was weak and sick at the time of his death, struggling with Crohn's Disease. At one time he weighed less than 100 pounds or 45 kg.

His father wishes he was there to help his son that fateful morning.

"Even though I'm 75 years old I would put all the strength I could to fend off those other SOBs."

Staff Sgt. Rick Tuza of the Calgary Police Service's homicide unit said the Mariani case, as well as five other unsolved homicide cases, are all active investigations.

Tuza's unit is working hard on the cases in hopes of bringing closure to the families.

"We can't bring back their child but we can give them a sense of closure that at least someone's held accountable," he said.

Police are also working to solve the slaying of Sarafino Virgilio, whose body was found in a vehicle in January. Officers are looking for 33-year-old Pablo Rodrigo Russell, considered a person of interest in the case.

Other unsolved cases are the deaths of Donny Tu, who was shot to death at the front door of his Edgemont home in May, Anto Slisko, a contractor found dead in a home under construction in June, and bartender Dexter Bain, who was shot to death while at work in November.

Police also announced Thursday that the death of Aref Nassereddine, whose body was found in his town house in March, has been deemed a homicide.