Jolly and her two accomplices, who helped her in supplying cyanide, which she gave to each of her victim was earlier arrested for plotting the murder of her husband Roy Thomas.
Shaju, a teacher by profession was questioned on four previous occasions and on Sunday evening he was seen on TV channels stating that he had no role in what happened.
But, the police probe team had asked him to come to the Crime Branch office at Payoli, near here and he promptly came, in the morning.
After 90 minutes of questioning, the police took him to the Vadakara office of Superintend of Police, K. G. Simon and after another round of questioning, Simon told the media that Shaju will be let off.
"Our probe is going on in the right direction and if required we will ask Shaju to come back again. We are in the process of verifying all aspects as many more will be also questioned. The State Police chief called me and said that if required, chemical examination in the probe can be given to foreign countries," said Simon.
In between Shaju's father Zachariah, a retired teacher who had told the media earlier that his son was trapped into marriage by Jolly and her elder son, was asked to present himself before the probe team.
In a related development, Jolly's friend and beauty parlour owner Sulekha denied that Jolly was her partner in business.
"I know Jolly for over a decade and she introduced herself as a lecturer at the National Institute of Technology and she was a regular client at my parlour. When her husband Roy Thomas passed away, my husband and I went to her home. She said her husband passed away due to a cardiac arrest," said Sulekha.
Meanwhile on Monday, 22-year old Rohit, said that he has given a complaint to the police after hearing the way the deaths occurred in the family serial murder, was similar to the way his father passed away.
"Why I decided to give the complaint was my father (Ramakrishnan, a local Congress worker) also died in the same manner as the six deaths that took place in the family of Jolly. My father passed away in 2016. He came from outside and had food and soon collapsed and died. In 2008, my father had sold a property for Rs 55 lakh, but we do not know where it has gone. We do not know Jolly, but we know Sulekha and her husband, who was my father's friend. We want to know what happened to the money," said Rohit.
A former Sub-Inspector of Police Raman Unny, who had probed the death of Roy Thomas told the media that there was no complaint given by anyone, even after it came to light that the death occurred due to cyanide consumption.
"Neither his wife (Jolly), his family members, friends or anyone came up with any complaint then and hence there was not at all an iota of suspicion that it was a murder, but all thought it was a suicide as the person was in deep financial crisis. I will definitely appear before the present probe team, if I am asked to, as it's my duty as a former police official," said Unny.
Raji Thomas, sister of Roy Thomas, told the media that she knew that Jolly and Shaju were in a relation and were planning to get married.
"What was shocking was their relation blossomed weeks after my brother passed away and hence when they got married soon, it was not a surprise to me," said Raji Thomas.
Meanwhile, the police probe team on Monday took statements from a retired revenue officer who had helped Jolly to register property, which the police has found out was done using fake and forged documents.
Also, on the radar of the probe team are few others which include local level political leaders, with whom Jolly had regular contacts.
All these mysterious deaths took place in the family of retired government official Tom Thomas.
The first to die was his wife and Jolly's mother-in-law Annamma, a retired teacher, in 2002. She was followed by Jolly's father-in-law, Tom Thomas, in 2008. In 2011, their son and Jolly's husband Roy Thomas died. Then Roy's maternal uncle Mathew died in 2014.
The next year, two-year-old child of Sily, a relative by marriage, died. In 2016, Sily also passed away.
The police began the probe into these deaths after Roy Thomas' brother Rojo, settled in the USA, approached the Superintendent of Police and expressed suspicion over the mysterious deaths.
Once convinced with Rojo's revelations, the police exhumed the mortal remains of the deceased persons from graves and sent them for forensic examination. The initial reports indicated to poisoning.
( With inputs from IANS )