Most Employers will go through stages where they have a great working team and there are no issues to contend with. Then out of the blue, there will be something you will have to address; disciplinary investigation.
Generally, the severity of the issue will determine the process that an employer follows. Even in small teams or small businesses that are built around friends and family, there comes a point where every business owner must address a conduct issue within their business.
The first port of call for most employers is either the ACAS Code of Practice, or their disciplinary procedures that are laid out in their employee handbook and/or contracts of employment. It is best practice to follow the ACAS Code of Practice as it is a process that supports the employer follow a fair process and come to a reasonable finding.