There are many pieces to a criminal case. There are procedural matters, physical evidence, and witness testimony that all must be addressed, and failing to do so properly could result in undesired consequences. However, when it comes to witnesses, a criminal defendant must be very careful, as certain actions towards those individuals could result in additional criminal charges that can carry significant penalties.
Under federal law, it is, of course, illegal to kill or attempt to kill an individual with the intent to prevent that individual from testifying, producing a document, or communicating with law enforcement or the court. Yet, it is also illegal to use force or the threat of physical force to influence or delay a witness's testimony. It is also against federal law to use threats of physical force to persuade an individual to destroy or alter anything that would affect its integrity when presented to the court.
The penalties for these crimes are quite serious. A conviction for witness tampering via death or physical force could result in up to 30 years in prison. The threat of physical force could land an individual in prison for up to 20 years. A 20 year sentence may also be handed down to an individual who corruptly alters, conceals, or destroys documentation. Even those who corruptly delay court proceedings could be found guilty of this crime.
With all of this in mind, those facing federal drug charges, along with their friends and families, should be careful how they act around witnesses, what they say around them, and how they treat potential evidence. If an individual is accused of witness tampering, then they should be sure to seek legal counsel to fight the allegations.
Source: Legal Information Institute, "18 U.S. Code § 1512 - Tampering with a witness, victim, or an informant," accessed on Dec. 4, 2015