Apparently around 1 in 3 Americans, according to this Monmouth Poll from last year: https://www.monmouth.edu/polling-institute/reports/monmouthp...
"About 1 in 3 (32%) think that illegal immigrants are more likely than other Americans to commit violent crimes like rape or murder. This marks an increase in this view from prior polls (21% in 2019 and 17% in 2015)."