SP state president Akhilesh Yadav, who met Sachan's family, assured them that he would raise the demand for a Central Bureau of Investigation inquiry into the case in Parliament to ensure that they get justice, a party statement said.
"Dr Sachan's family is getting death threats and they require proper security," Yadav said and described government's actions as "unpardonable".
Accusing government officials of "acting as ruling party functionaries" by making announcements on behalf of the Bahujan Samaj Party, Yadav demanded stern action against them.
Yadav said a CBI inquiry into Sachan's death would not only nab the culprits in the case but "also expose the scams worth thousands of crores of rupees in the health department".
The main accused in the murder of Chief Medical Officer (family welfare) B P Singh, 52-year-old Sachan was found dead in jail hospital toilet on Wednesday night after which the government ordered a judicial probe into the incident and suspended five jail staffers, including a jailor.
His postmortem report revealed nine injury marks on the body including on neck, elbow, thigh and wrist.
A case of murder was registered by the police on Sunday following his wife's complaint.