The 26-year-old actress was allegedly abducted by Amit Kumar Jaiswal and Priti Elvina Suri and later murdered in Gorakhpur district, Uttar Pradesh.
According to police, the actress was lured by the duo, who promised her a big budget movie.
The accused demanded a ransom of Rs 15 lakh from Thapa's family thinking she belonged to an affluent family. The accused made a ransom call to her family even after murdering her.
The duo were arrested from Bandra area after they confessed to their crime.
Meanwhile, police teams have been sent to Uttar Pradesh, to trace the body of the victim.