Peter returned to Mexico once again on 22 February 2019 having not fought in two years. He appeared at the Cheers Bar & Grill in Tijuana knocking out Gerardo Escobar in just 44 seconds of the fight starting. On 26 March Peter signed a promotional contract with Salita Promotions and was announced to fight Mexican journeyman Mario Heredia (15–6–1, 13 KOs) on 13 April at the Boardwalk Hall in Atlantic City on the undercard of Claressa Shields vs. Christina Hammer. Prior to the fight, Heredia was 2–5–1 in his previous eight bouts. Peter lost an eight-round split decision to Heredia, which took place at the Adrian Phillips Theater. Peter scored a knockdown in round-three yet was unable to finish Heredia, who fought on and prevailed by scores of 77–74 and 76–75, with the third judge giving Peter the nod via a 79–72 margin.