Prosecutors say Kling killed William Budfuloski in 2003 in an effort to gain control of the business Budfuloski owned. Prosecutors also say Kling killed Budfuloski's son a year later.
In addition, Kling was convicted of killing Budfuloski's dog, who guarded the office.
Police say Kling had used 104 aliases prior to his arrest.
The Associated Press contributed to this story.