If specific agency, for example the FDA or the EPA, is indicated that us a good place to start. If it is unclear contact the FBI. The agents will access and either investigate or refer you to the appropriate federal agency.
Please do NOT use this answer/response to say or do anything regarding your situation. This answer/response is based on the information provided in the question asked and requires a much more complete context than is available in this public forum. BEFORE you say or do anything consult with an experienced Federal and/or state criminal defense attorney in your jurisdiction who will listen to you and your concerns.
There are various ways to do this. If the crime is fraud and costing the Government money, then you may want to hire an attorney first to guide you. There could be a reward.
Gold, Benes, LLP offers free telephone consultations between 10 and 4 weekdays.
The first question I will ask you is what crimes are being committed? "Violating US Federal Laws," is an awfully broad statement. Is a specific PERSON violating these laws while working for a corporation, or is the CORPORATION violating these laws? There actually is a difference.
If you work for the corporation, or are a FORMER employee of the corporation, then you have to present some evidence to the agencies to which you will report, demonstrating that you are not simply acting out of malice towards the person or corporation.
I would suggest that you sit down, and make a list of all of the items that you think are or might be violations of the law, including a list of all of the persons and corporations you think are involved, and then submit them to the local Assistant US Attorney's office, with a copy to the State Attorney General's Office. This way, both Federal and State authorities will be put on notice that the activity you are alleging is occurring.
In addition, as someone who is REPORTING the wrongdoing, you should retain counsel for THREE reasons.
1. You need someone to help you through the deposition process when they interview you.
2. There may be a financial reward for reporting such crimes.
3. They can help you maintain your anonymity as a whistleblower.
You should retain this counsel BEFORE you submit the information to the authorities, and seek advice from them on HOW to do so.
Look for a Qui Tam/Whistleblower attorney on this site.
This does not constitute legal advice or the engagement of my services as an attorney.