Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
prōsĕcūtor (prōsĕquūtor), ōris, m. [prosequor], an accompanier, companion, an attendant (post-class.), Dig. 48, 3, 7; Cod. Th. 8, 5, 47; 10, 72, 1; 12, 6, 12 et saep.: caterva prosecutorum, Sid. Ep. 4, 8.