Nathalie Martinez says she’s just “going up the ladder.” Jacob Jimenez said he is gaining life experience. Ian Garibay said he is being given the opportunity to help people, which is all he’s ever wanted. All three are testing the waters of law enforcement by joining the Tustin Police Department’s part-time detention program, which can create an opportunity to become a police officer through a new program launched in 2019. “We use it as a farm system. So far it’s been good,” said Sgt. Robert Nelson, who oversees the program. Two former detention officers have joined the Tustin Police Department…