Vellanki Simhadri alias Shiva resorted to the killings in Krishna, East Godavari and West Godavari districts between February 2018 and October 16, 2019.
West Godavari Superintendent of Police Navadeep Singh announced the arrest of the serial killer at Eluru on Tuesday evening.
The police investigations revealed that after suffering losses in real estate business, Simhadri started cheating with claims of possessing supernatural powers. He was conning people in the name of hidden treasure and precious stones and promising to double their gold.
Hailing from Eluru town, the accused collected money and gold from his victims with a promise to give them "rice-pulling coins', the comic which is believed to bring prosperity. After taking token money he used to give them cyanide-laced 'prasadam'.
"He was using cyanide to kill his victims because no changes are observed in the bodies of the deceased and it appeared a natural death," the police officer said.
He said the killings came to light during investigation of a suspicious death in Eluru last month. K. Nagaraju (49), a government teacher, had died on October 16 after he had left his house with cash and jewelery to deposit them in the bank. Simhadri had fooled him into paying Rs 2 lakh in exchange for a coin, which is believed to bring prosperity.
An autopsy was conducted after Nagaraju's family voiced suspicion over the cause of the death. During interrogation, Simhadri confessed to the crime.
Since families of at least 10 contacts in Simhadri's mobile phone had reported suspicious deaths since last year, the police launched in-depth investigations. All victims are suspected to have died after consuming cyanide-mixed 'prasadam'.
Police found that Simhadri's victims included his own grandmother and sister-in-law. FIRs were registered in only four cases.
Police plan to exhume bodies of three victims, who were buried. Investigators hope to gather more clues to build a strong case against the accused.
Police also arrested Sheikh Aminullah, who runs nickel-coating workshop in Vijayawada, for allegedly supply cyanide to Simhadri.
( With inputs from IANS )