Just because an individual is charged for a crime by a state government such as Texas does not mean the federal government cannot also apply charges in serious situations. This generally happens in cases of interstate flight, human trafficking, or major drug cases. However, the most severe cases for federal law enforcement agencies are when crimes are committed involving firearms. Not only do states maintain laws regarding firearm transfers and ownership, federal agencies such as the ATF are also very concerned when there are any types of crimes involving guns. And, this especially applies to illegal firearms.
It is not necessary for a defendant to be accused of criminal activity across state lines for federal officials to apply charges as well. And even though many times they cooperate regarding which one will handle the prosecution, the truth is that both can prosecute the same individual for additional felonies when charges are applicable. Texas is among the many states with black market firearms suppliers, and those who are apprehended are often chargeable on both the state and federal levels.
Drug activity is also prevalent in many southern states when illegal substances are being smuggled into the northern regions of the nation. Much of this activity is conducted by gangs that also have extensive firearm stashes for protection when transporting and transferring contraband. Regardless of the amount, all charges associated with trafficking major amounts of drugs are serious felonies even without the use of firearms, and charges can be enhanced significantly when guns are also discovered with any controlled substances.
The truth is that the use of firearms can make any criminal charges worse regardless of the government agency prosecuting the case. The Bureau of Alcohol Tobacco and Firearms and the DEA both work together with the state of Texas when serious criminal activity is being prosecuted.