The 49ers likely will have to decide whether to retain troubled linebacker Aldon Smith for a fifth season without a resolution in the DUI and gun-possession charges he is facing. The district attorney’s office and Smith’s defense team did not reach a plea deal – something the 49ers thought was a possibility, albeit an unlikely one – at a hearing in Santa Clara County Superior Court on Tuesday. A new hearing date is scheduled for May 12. Smith, 24, is facing DUI charges related to the September incident in which he was found at the wheel of a vehicle that came to a stop in a residential front yard. He also faces three felony counts of illegal possession of assault weapons that were found at his home in the aftermath of a raucous 2012 party that ended with Smith being stabbed in the abdomen. It’s possible the case could be resolved before Smith’s next court date. But that probably won’t occur before Saturday, the deadline for triggering the fifth-year option on Smith’s contract. Asked last week whether the 49ers had enough information about the cases to make a decision, general manager Trent Baalke said, “I don’t know if we’re ever going to have enough information. You never have enough, do you?” Smith, who holds the franchise’s single-season sack record and is one of the most talented pass rushers in the league, is entering the final year of his 2011 rookie contract that will pay him $2.3 million this season. The fifth-year option, which already has been triggered for a number of players in Smith’s talent-laden 2011 draft class, would pay him $9.8 million in 2015.