While nine accused were discharged, one of them -- Kari Satheesh -- had failed to file his appeal at the High Court against the Central Bureau of Investigation (CBI) court judgement which sentenced all of them to life term.
Satheesh was the one who had stabbed Paul Muthoot.
While the High Court cancelled the life term of the eight accused, other charges will stand, but with all of them having served more than nine years in prison, they are expected to walk out of the jail.
Paul's father, M. George Muthoot, said he will approach the Supreme Court against the High Court's verdict.
Paul belonged to the wealthy Muthoot business family which is into private banking and has numerous other business ventures.
The murder mystery was first investigated by the police and later transferred to the Crime Branch which arrested 14 people.
Later, Paul's father sought a CBI probe. The central probe agency took up the case in January 2010 and the CBI court in the state capital on September 1, 2015, sentenced all the accused to life term.
The motive for the crime, according to the investigating agency, was the intervention and altercation by the accused after Paul's speeding vehicle knocked down a two-wheeler near Alappuzha.
The accused and his group of men who saw this followed Paul and stopped his vehicle and after a verbal altercation, stabbed him to death.
The probe team also found that the gang was on their way to eliminate another person when they picked up the quarrel with Paul that resulted in the murder.