Dr Dharmendra Pratap Singh has now been arrested in connection with Rakhi Srivastava's death after allegedly sedating her.
She went missing in June, not long after remarrying following her split with Singh.
The second hubby was an initial suspect but police in Gorakhpur, India, detained Singh and two alleged associates, Pramod Kumar Singh and Deshdeepak Nishad, on Friday.
And cops say Singh regularly changed Ms Srivastava's Facebook on her phone in the months since in an attempt to fool them.
But her phone was found in October.
"This made Dr Singh a prime suspect," a police source said.
"However, even after killing Rakhi, they kept updating her social media account through her mobile phone."
Ms Srivastava's family has made an emotional plea for more information.
The investigation continues.