John Sugden gets caught after a major incident where he falsely accuses his brother Robert Sugden of threatening him, then jumps from a gorge taking his husband Aaron Dingle with him. Both John and Aaron are badly injured and rushed to the hospital, with Aaron put into an induced coma. Robert is wrongfully arrested for attempted murder based on John's lies and fabricated evidence. Later, when John recovers consciousness, he continues to lie to the police to keep Robert implicated. This sequence of events happens around early to mid-September 2025 in the storyline, with recent episodes revealing significant developments in John's scheme and his eventual confrontation with the authorities.
In summary, John is effectively caught and under police scrutiny by early to mid-September 2025, after the dramatic fall incident and his ongoing deceitful behavior to frame Robert.