The Palm Beach Gardens Police Department rarely needs to investigate homicides.

The city, located in Florida, is a recreational holiday spot, popular with retirees and seniors.

There are more than 50,000 residents living there.

When officers found the body of Alan J. Abrahamson on January 25, they were stumped.

The 71-year-old owned a house in the gated city with his wife Linda, had children, stepchildren and grandchildren, was a golfing fan, had a busy social life and was well liked by everyone.

CCTV footage at the community’s north gatehouse showed Mr Abrahamson walk past at 5.53am. He had something in his left hand but it was too dark to make out.

Exactly 37 minutes after he walked off camera, a gunshot was heard.

A dog at a nearby golf course heard the shot and lead its owner to a nearby field where Mr Abrahamson’s body was lying near a footpath 90 metres from the security camera.

He was lying in a pool of blood. A bullet had exploded in his chest, killing him instantly.

There was no sign of a weapon, no foot tracks near the body and his wallet and phone were still in his pocket.

Investigators spent weeks questioning locals and family members scouring the crime scene for any clues.

Although the field work turned up very little evidence, the case took a turn when Linda Abrahamson helped officers unlock her late husband’s mobile phone.

Investigating officers searched through Mr Abrahamson’s phone records and found clues that lead them to doubt the original homicide investigation.

Mr Abrahamson’s mobile phone had several points of interest in its search history including:

July 7, 2009: “Suicide” and “How to commit suicide”

April 10, 2012: “Life insurance suicide”

March 17, 2016: “Undetectable suicide methods”

February 21, 2017: “If shot in the heart do you die instantly?” and “Can you have a gunshot suicide with no weapon present?”

February 23, 2017: “YouTube/SEG, Suppressors, Jefferson Silencer on Walther PPK’s Suppressed .380”

August 28, 2017: “How many cubic feet of helium do you need to raise one pound?”

January 23, 2018: “Helium suppliers near me”

January 24, 2018: “Dawn and Dusk times”

There was also an email regarding an order he placed on Christmas Day 2017 from an online science supply company.

Mr Abrahamson had purchased a A$75 weather balloon.

His Google Maps history also showed that he made a detour on one of his morning walks, to an industrial supplies store in West Palm Beach two days before his death.

Detectives visited the store and obtained a copy of Mr Abrahamson’s receipt for a 12-square foot helium tank.

They re-interviewed friends and family and nobody could confirm whether Mr Abrahamson had any hobbies that would require a weather balloon or helium tank.

They also walked the path that Mr Abrahamson took on the morning of his death.

It took 37 minutes before he disappeared from the gatehouse surveillance footage to when the gunshot was heard.

Even at a slow pace, detectives could walk the distance between the two sites and back again in a short four minutes and three seconds.

They also found rubber band and lengths of string near the crime scene that were similar to ones found at Mr Abrahamson’s home.

The man’s blue shirt was covered in blood, however one investigator noticed an irregularity in the blood stains.

A thin trail of blood threaded away from the blood pooled on Abrahamson’s shirt and up his shoulder.

“Possibly indicating that something was in the blood and dragged across the top of his shirt,” a police report read.

Investigators theorised that Mr Abrahamson had “tied a gun to a string and attached it to a weather balloon”.

“Once the shot was fired the weather balloon ascended carrying the weapon from the scene,” an investigator wrote in the report.

“Although the theory seemed far-fetched, it was plausible.”

Researchers could only find two other examples of something like this happening.

The first was in New Mexico, where a man had tried to shoot himself with a gun attached to a balloon but the balloon got caught in a nearby cactus.

The only other example was from a 2003 episode of the fictional television series “CSI: Las Vegas.”

Police released their final report last week concluding Alan J. Abrahamson’s death was a suicide.

The balloon and gun have not been located and workers who look through the many lakes around Palm Beach Gardens for sunken golf balls have been asked to keep an eye out for the helium tank.

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