The four - the retired judge, his wife, son and another person were arrested following a statement of the woman, who is fighting for her life in the SCB Medical College Hospital here, Cuttack Deputy Commissioner of Police (DCP) Pravin Kumar told newsmen.
The woman, who is in her early 30s was found by morning walkers near the spur of Mahanadi barrage here yesterday and reported the matter to the police, who rescued her.
Kumar said the judge's family had hired goons to throw the woman into the river after intoxicating her.
The police have launched a manhunt to nab the goons, who allegedly took Rs 3.5 lakh from the retired judge for the crime.
The woman, who is about 20 weeks pregnant, in her statement said she was married to the judge's son about five years ago. However, the in-laws wanted her to abort the baby so that they could arrange a second marriage of their son.
Police investigation revealed that she resided with the retired judges family at Chandrasekharpur area of Bhubaneswar and corroborated her statement.