Unni, who is also an actor, presently being questioned by the investigating team led by Nedumangad DySP.
The development comes days after his estranged wife and actress Ambili Devi had accused him of cheating on her.
The incident occurred while the police and Fire & Rescue personnel were retrieving the body of an autodriver from the river. He died by suicide in the same manner.
With several people choosing the spot to take the extreme step, the bridge apparently have become a suicide point.
A suicide note, suspected to be written by the deceased nun, was recovered from her room. As per the note, no one was responsible for her death and she was ending her life due to health issues.
The body of Branch Manager K Swapna, 38, was found on Friday morning. Swapna's body was first seen by another woman employee who arrived at 9 am.
Siddharth alias Siddu, 17, was reportedly enacting a suicide scene on his mobile phone when the bedsheet he was using got fatally tangled around neck at his residence around 9pm on Thursday.
Neighbours who reached the house on noticing the fire rushed Saramma and Liji to the Alappuzha Medical College, where Saramma succumbed to her burn injuries.
Geddert, who had ties to disgraced team doctor Larry Nassar, was charged earlier on Thursday with human trafficking and sexual assault.
He has represented the Dadra and Nagar Haveli in parliament since 2004.