HOUSTON --There are new questions after a group of suspects were arrested for armed robbery, then released from jail even though they face federal charges. The five men had originally been taken into custody to face state charges, but then the federal government got involved. Shortly after that, they were released from jail. But investigators say that should have never happened. The U.S. Marshal's Service has to make a formal request to temporarily take custody of an inmate in order to prosecute them in the federal system. But the normal operation procedures in this case failed somewhere along the line. Three months ago, Houston police arrested the men in connection with an armed robbery outside a southwest Houston business. Fast forward to last week when on June 22, the state dropped the laundry list of criminal charges against Marcus Clemens, Michael Waterman, Donnie Stroud, Eric Eakin and Juran Moore. That happened just a week after a federal grand jury indicted them. But the five remained behind bars in the Harris County Jail until late last week when instead of being transferred to federal custody, four of the men -- Waterman, Stroud, Eakin and Moore -- suddenly found themselves free men, walking out the front door of the Harris County Jail. The question we asked and authorities are wrestling with is why and who's to blame? When we started digging for answers, a Harris County Sheriff's Office spokesman told us, "If there were federal holds, the Harris County Jail would have held them. There were none." Since the case is being prosecuted by the U.S. Attorney's Office, we called over there and a spokesperson told us, "All appropriate paperwork was filed on June 15. We are not involved in the execution of warrants or writs." That's the responsibility of the U.S. Marshal's Service. A spokesman told us a formal request for Harris County to turn them over was made a day before their scheduled federal court date. Deputy U.S. Marshal Alfredo Perez claims the fax sent to the county jail was followed up with a phone call which is normal procedure. "We don't know what happened. It's unfortunate that sometimes something like this happens. Whatever procedures failed or what may have caused this error are going to have to be reviewed as to not let this happen again," said Perez. Currently, three of those four men are behind bars in federal custody, while one is still a fugitive. A spokesman with the U.S. Marshal's Service says this matter is still being looked into.