Landslides are among the most destructive geohazards, often triggered by extreme rainfall and intensified by fragile geological settings and human activities. On July 30, 2024, a catastrophic rainfall-induced landslide struck Vythiri Taluka in Wayanad district, Kerala, India, causing fatalities and widespread destruction. This study employs Persistent Scatterer Interferometry (PSI) using Sentinel-1 SAR data along with GNSS observations to investigate pre-event deformation and slope instability. PSI analysis of 33,253 scatterer points revealed cumulative Line of Sight (LoS) displacements up to 65 mm, with abnormal variations of ~ 20 mm detected on 20th July, ten days prior to failure. Average displacement rates of 2.0 mm/year and localized rates up to 5.0 mm/year near the crown highlight significant precursory deformation. GNSS-derived E-W compressional and N-S extensional strain confirmed localized active fault systems in the region. Integration of rainfall records demonstrated extreme precipitation (> 360 mm in 24 h) as a critical triggering factor, acting in concert with fractured lithologies and tectonic activity to destabilize slopes. The findings suggest that a weak zone formed well before the event, with deformation serving as a precursor to failure. This study underscores the importance of continuous monitoring with PSI-InSAR for landslide hazard mitigation.