The announcement about Singh's election was made by party's national general secretary Bhupendra Yadav at Uttar Pradesh BJP office.
Suresh Rana and Sangeet Som were accused in the 2013 Muzaffarnagar riots, while Nand Gopal Nandi faced a bomb attack in 2012 in which a journalist was killed.
BJP MLA Kamlesh Saini said that the two sub-inspectors showed a total lack of respect for a public representative.
On October 8, BJP leader Chaudhary Yashpal Singh was gunned down in a similar manner in Deoband, and two days later, another leader called Kabir Tiwari was killed in Basti.
After getting rid of the SBSP, the party is now preparing to sideline the Apna Dal in the upcoming Assembly bypolls.
87-year-old Singh will arrive in Lucknow on Thursday and will enroll as a Bharatiya Janata Party (BJP) member.
A special investigation team has been constituted to probe the rape of an 18-year-old woman, allegedly by BJP MLA Kuldeep Singh Sengar and his brothers and the custodial death of the victim's father.