He was first suspected because he escaped the Book Depository, the only employee to run. After he murdered Officer Tippet, it became fairly obvious-- why would an innocent man murder a police officer?
Oswald
Lee Harvey Oswald was arrested at the Texas Theatre at 1.45pm on 22/11/63
Harvey Lee Oswald as he is seen on the 6th floor of the Texas School Book Depostitary.
If you mean JFK, there are no reasons why Oswald didn't kill him, because Oswald did kill him.
Lee Harvey Oswald.
Lee Harvey Oswald
Oswald was a Marine and JFK was in the Navy.
Oswald.
Lee Harvey Oswald
1962
He shot JFK.
Lee Harvey Oswald!