LEE COUNTY, Fla. - Two murders... within five days... and Lee County Sheriff's detectives believe Brian Casey is responsible for both.

Ryan Vanderson and Larrick Sikes lost their lives within just five days of one another. Major Jim Jones said, "I am sure the question is how are Sikes and Vanderson related? And they're not. We don't believe that the two cases are related."

The common denominator in both? Brian Casey.

Here's how deputies say it all happened:

--October 15th, Casey shot salesman Ryan Vanderson during a business meeting at Vanderson's home, and then, torched the house.

--October 20th, Casey is accused of strangling Larrick Sikes, dumping his body on Luckett Road Extension, and setting it on fire.
That same evening, Casey was taken into custody, and charged the next day with Arson and Murder in Vandersons' death.

--November 3rd, Casey was charged with 1st-Degree Murder in Sikes' death.

Investigators also arrested and charged 30 year-old Daniel Ventura with 1st-Degree Murder and Kidnapping for his role in Sikes' murder.

"Casey particularly didnt care for the other guy, Sikes, and that is the reason why he was murdered," Jones said.

Some of Larrick Sikes' family tell us Brian Casey acted as a friend, helping him find work. They had no idea Casey could commit such evil. The same shock resonated with friends of Vanderson, wondering why someone would kill a man with no known enemies.

"There was some anger there, that somebody in a calculated way had taken the life of a great friend, taken the life of a great father," Vanderson's friend Brad Beckwith said.

Detectives are also on the lookout for a person of interest - 36 year old Lawrence Rasnick. He's known tofrequent the East Fort Myers area, and is believed to be armed and dangerous.