It is not a civl rights violation for an employer to have an investigation due to a violaton of the employer's rules. Under Federal civl rights laws you are not guaranteed the rights under Miranda for an employer's investigation. The only entity that is required to read a person Miranda rights is the police and only in the case of an arrest. Miranda rights to not apply to an employee who is involved in an employer's investigation. There are may rights a person gets under criminal law, such as being able to 'take the 5th amendment' to protect yourself from incriminating testimony, that are not available under employment laws.
If you are a member of a Union and working under a union contract, you may have certain additional rights during an employer investigation. If you are not a member of a union and are not working under an employment contract you are considered an at will employee. As an at will employee your employer is allowed to require your participation in these invetigations, discipline you, and even terminate you for any reason EXCEPT when the employer's motive is discrimination. Illegal discrimination is based on age, sex, race, nationality, color, disability, pregnancy, religion, marital and military status. You may want to look at www.eeoc.gov regarding your rights if you are discriminated against.
As for having a lawyer or a respresentative to protect you, a union member is usually represented by a union official, those not in a union should check with the Human Resources for the company's policy on having a 3rd party outside representative. Under the law an employee is not guaranteed a representative/lawyer for internal employer investigations. However, your employer can allow this.
Civil rights laws are in place to protect against those who act in violation of constitutional protections under color of law. Not every wrong is a civil rights matter. You should check with a lawyer familiar with the specific regulations and laws that exist under the Choctaw nation locale, before things go any further.
Good luck to you.
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Generally, a private employer is not required to read Miranda rights (or any other kinds of rights). However, a public employer may be required to do so, if the questioning may cause the employee to incriminate herself, and if the employee is in custody or otherwise restrained from leaving during the interrogation process. Miranda warnings are just one of several kinds of warnings and rights that public employers (i.e. government agencies) may be required to provide an employee who is the subject of an internal investigation. The employee may also be entitled to a Loudermill hearing, to Weingarten rights, and to Garrity and Gardner warnings -- all of these terms being named after other famous cases like Miranda. If the nature of the employer's questioning can lead to termination from employment or to a criminal prosecution, then I would recommend that you have an attorney on hand.