Not getting release from organization

Employee(Senior level) was serving notice period (3 months) just 10 days before last working day, company legal team initiated an investigation against employee. Legal team has issued suspension notice stating suspension pending enquiry. During investigation, the allegation was One of the employee's team member has used company's laptop to do screen design for some other company. Legal was trying to corner employee that his team member did that work based on his manager's request. (employee whose suspension was issued) . However legal was unable to prove any of these both employee's instruction and his team member used his company's laptop for some other work. Legal team was unable to conclude their investigation mean while company has extended employee's last working day further 13 days. End of 13th day company was forcing employee to accept a Show cause notice, which was completely irrelevant to the context of investigation. Hence employee did not take show cause notice. Employee has surrendered all company assets including ID card. Employee has discussed with Lawyer, Lawyers are advising that company cannot extend last working day once separation is accepted. Since employee will be using other opportunities. However now company HR and legal both are not relieving employee. What is the next steps? They haven't deposited last month salary as well