[3] The victims were a vacationing upper-middle-class family from Lathrup Village who were shot and killed inside their Lake Michigan holiday cottage, with two decedents also bludgeoned with a hammer prior to death.

The firm strategized advertisement campaigns for businesses with the Detroit region;[14] he also worked as a commercial artist, executive and publisher for Impresario magazine, which focused on cultural issues such as the arts, theatricals and music and was also based within his one-story Southfield office.

[13] In the summer of 1968, the Robisons embarked on their annual vacation to the Blisswood Resort community within the small town of Good Hart.

The five-room cottage itself was situated at the end of a long private driveway within a heavily-wooded area and which at one section runs alongside a 100-foot bluff close to the Lake Michigan shoreline.

[20] On June 23, one of the Robisons' traveling companions, 18-year-old Norman James Bliss (the son of the caretaker of Blisswood Resort and a close friend of Richard Jr.), was killed in a motorcycling accident while returning to Good Hart from nearby Cross Village, reportedly while intoxicated.

Upon receipt of this news, Richard Sr. paid personal condolences to Bliss's parents at their Good Hart holiday home, offering to pay for the teenager's grave marker and flowers or a wreath.

[22] He also explained the family would be unable to attend the funeral as they were due to fly from Pellston Regional Airport to Kentucky, then Florida, with view to purchasing real estate and would "not be back [to their cottage] for a couple of weeks."

[5] Due to the conversation Robison Sr. had with the caretaker of Blisswood Resort the previous evening pertaining to impending travel plans, neither the Robisons' travel companions nor the caretakers of the resort became suspicious when the family were not seen for several weeks despite the fact the family's Ford LTD station wagon plus their rented Chrysler Newport remained parked close to the cottage.

[26] The final confirmed sighting of the Robisons occurred at approximately 4:30 p.m. on June 25,[14] when two individuals tasked to trim trees within the grounds of Summerset left the property.

The murders evidently began when the assailant was outside the property, as five .22-caliber semi-automatic rifle gunshots[27] were fired through a rear window of Summerset Cottage at Richard Robison Sr. as he sat in a chair.

[19][n 3] The perpetrator then entered the cottage through an unlocked door and killed the remaining five family members—Shirley (40), Richard Jr. (19), Gary (16), Randall (12), and Susan (7)—with shots to the head and body from both the rifle and a .25-caliber semi-automatic pistol.

[6][30] A single bloody footprint on the floor would lead investigators to conclude that one person had committed the murders, and this individual had most likely closed all the curtains to the cottage and crudely attempted to cover the bullet holes in the window from his initial salvo with a piece of cardboard before turning on the heating within the property, then locking the door to the premises before leaving the scene.

[9] Bliss found both doors to the property locked;[33] he pried open the molding to gain entry to the cottage only to discover the crime scene.

[36] The time-lapse between the homicides and their discovery in addition to the perpetrator having turned the heating on within the property had resulted in the decedents' bodies being in an advanced state of decomposition, thus destroying potential physical evidence.

[38] All individuals whom the Robisons were known to have encountered in the nine days they had spent at Good Hart were eliminated from the inquiry, and theories pertaining to potential family links to organized crime circles were also discounted.

[40][n 5] By the second week of the investigation, the Michigan State Police and the Emmet County authorities strongly suspected that one of Richard Robison's senior employees, 30-year-old Joseph Raymond Scolaro III, had been the perpetrator.

[24] Nonetheless, Robison's receptionist, Glenda Sutherland, informed investigators Scolaro had abruptly left his office shortly after receiving the first phone call from his employer, and subsequent inquiries revealed he had not been seen or heard from by his family, friends or colleagues between 10:30 a.m. and 11 p.m. on the day of the murders, when he returned to his Birmingham home.

[11][n 6] Subsequent inspections of company financial records revealed that in the weeks prior to the murders, Scolaro had authorized a significant increase in his salary and expenses without his employer's knowledge.

[45] A November 1969 examination of a private Union Lake firing range owned by Scolaro's father-in-law produced several shell casings forensically proven by the Michigan State Police Crime Laboratory to source from the AR-7 firearm used in the Robison murders;[43][n 7] this revelation was considered conclusive evidence of Scolaro's guilt to the two investigating police agencies.

[47] In addition, although the firearm was still missing,[6][48] a neighbor informed police he had seen a .22-caliber AR-7 rifle in Scolaro's home shortly before the Robison murders.

Although the actual pistol used could not be traced, Scolaro's wife, Lora Lee,[50] confirmed to investigators she had been with her husband at the Birmingham Gun Club when he had purchased two firearms of this caliber on February 2, 1968.

[6] Several spent Sako .25-caliber cartridges had been recovered from the crime scene; this was a rare Finnish brand sold only for a limited time in Michigan in January and February, 1968.

[47] The following month, Emmet County prosecutor Donald C. Noggle and Attorney General Frank Kelley ruled that insufficient evidence existed to bring formal charges against Scolaro, referencing the fact that although the spent shell casings recovered from the private firing range matched those used in the murders, the two firearms used in the commission of the murders had not been recovered.

He would later sell the magazine, and also founded another firm he named Dimensional Research Inc.[40] Upon orders of the National Bank of Detroit, executors of the Robison estate, Summerset Cottage was demolished in the spring of 1969 due to an executive ruling the building was no longer habitable.

Upon reviewing the accrued evidence, Patterson informed Oakland County Assistant Prosecutor Ronald Covault: "We are going to charge [Scolaro] with murder.

[55] When Scolaro learned of his likely impending indictment resulting from this reopened investigation, he committed suicide by shooting himself in the head in his Southfield office on March 8, 1973.

[5] Their interments within Acacia Park Cemetery followed a service attended by several hundred mourners and which saw the caskets of Richard Sr. and Shirley flanked by those of their four children.