Spectroscopic targets (red squares) observed in Liller 1. Panel a: position of the targets in the plane of the sky with respect to the cluster center (marked with a cross). For the sake of reference, the two dashed circles mark the distances at 10^′′ and 37^′′ from the center. Panel b: target positions in the NIR CMD. Panel c: vector-point diagram of relative PMs determined from HST and adaptive optics observations. The red circle delimits the stars considered as likely cluster members in Dalessandro et al. (2022). Panel d: radial velocity of the 12 targets compared to the overall distribution of 244 stars measured in previous studies (Crociati et al. 2023; Alvarez Garay et al. 2024a; Fanelli et al. 2024).