A backpack with a name on it with a replica handgun inside led San Marcos police to arrest a man suspected in three sexual assault cases. Police said the name written in permanent marker on the backpack was Tyshane Thomas, who was taken into custody Tuesday afternoon and is facing a charge of aggravated sexual assault. Officials with the San Marcos Police Department said a witness called police after finding the backpack in a stairwell at the Sanctuary Loft Apartments in the 300 block of North Street. Officers found a black hooded sweatshirt, a black ski mask, a BB pistol that appeared to be a real handgun and several articles of women's clothing inside the backpack. San Marcos police Chief Chase Stapp called the finding a "huge break" in the case, which led police to arrest Thomas, 20, at the apartment complex, where police believe he lives with his girlfriend. During a five-hour long interview with investigators, police said Thomas confessed to three sexual assault cases and a burglary, all occurring in the San Marcos area. The first report of a sexual assault happened April 24 at the Cottages of San Marcos apartment complex, where police said a man had been hiding in the victim's bedroom and then sexually assaulted her. On April 30, police went to the same complex, where several residents said they'd just escaped from their apartment after a man broke in and threatened them with a gun. Two days later, two women called police after a man physically and sexually assaulted them for nearly three hours inside their apartment at The Retreat apartment complex. During the course of the investigation, Stapp told KSAT.com that "each of the crimes happened in the middle of the day. In most of the cases, the suspect found his way into the apartments through an unlocked door or window." After obtaining a warrant to search Thomas' apartment, officers found duct tape, zip ties and personal lubricant, which are believed to have been used during the sexual assaults. Thomas was recently a student at Texas State University studying criminal justice, according to SMPD officials. While Thomas is only being charged in the April 24 incident, Stapp said he expects additional counts for aggravated sexual assault and burglary in all three cases at the end of the day. According to online records, Thomas is still in the Hays County Jail and his bail has been set at $750,000. Stapp said at this time, police have not received any additional victims who Thomas may have also targeted. Thomas' girlfriend is not being viewed as his accomplice, Stapp said.  SMPD officials said the investigation is ongoing and anyone who may have additional information about the incidents is urged to contact the Police Department at 512-753-2108. RELATED STORIES: San Marcos police search for man who broke into apartment, sexually assaulted woman Residents taking preventative measures after 2 break-ins at same San Marcos apartment complex San Marcos PD searches for sexual assault suspect amid third break-in in over a week Texas Rangers, FBI called in to help investigate string of sex assaults in San Marcos