There are many investigations on former FBI agents!

Here is a sample:

Deputy Director McCabe Ethical Guidance and Recusal
Deputy Director McCabe Communications Regarding Spouse's Virginia State Senate Campaign
File Deputy Director McCabe Communications Regarding Spouses Virginia State Senate Campaign Part 01 of 01
File Deputy Director McCabe Ethical Guidance and Recusal Part 01 of 01
File Records Related to the Dismissal of FBI Director Comey Part 01 of 02
File FBI Director James Comey Climate Survey Results (2015-2017)
File Director Comey Letter to Congress Dated November 6, 2016
Director Comey Letter to Congress Dated November 6, 2016
Director Comey Memoranda of Communications with President Trump
Director Comey Letter to Congress Dated October 28, 2016
Records Related to the Dismissal of FBI Director Comey
File Director Comey Letter to Congress Dated October 28, 2016 Part 01 of 01
File Director Comey Memoranda of Communications with President Trump Part 02 of 02
File Records Related to the Dismissal of FBI Director Comey Part 01 of 02
File Director Comey Memoranda of Communications with President Trump Part 01 of 02
File Records Related to the Dismissal of FBI Director Comey Part 02 of 02