Here's a link to a PDF of all 68 OIG investigations re: DOJ
https://www.oversight.gov/reports/pdf-version?field_address_country=All&field_type_of_product%5B%5D=8&field_component_agency_%5B%5D=321
And here's a link to a PDF for the DoS OIG investigations:
https://www.oversight.gov/reports/pdf-version?field_oigs_submited_particip%5B%5D=155
And here's a link to Oversight.gov where you can look at any agency you'd like:
https://www.oversight.gov/investigations