The police watchdog is to investigate whether there were "any missed opportunities" by officers before a two-year-old boy and his father were found dead at a flat.
Bronson Battersby was discovered starved to death alone next to his 60-year-old father Kenneth, who had suffered a fatal heart attack over the Christmas period.
The toddler's body was found with his dad's at their home in Skegness, Lincolnshire, on 9 January, two weeks after they were last seen alive on Boxing Day by a neighbour.
It is believed Kenneth Battersby died days later, leaving Bronson with no access to food or water at the flat.
Lincolnshire Police has referred itself to the watchdog, the Independent Office for Police Conduct (IOPC), which has confirmed the force's actions before the pair were found dead would be the subject of an investigation.
The force was contacted by a social worker twice about Bronson's welfare during the week before the bodies were found.
It comes as Bronson's mother said her child was two inches too short to reach the fridge.
Sarah Piesse, 43, told The Sun: "If only Bronson was a little bit taller, then he would have survived. The fridge would have been packed with Christmas leftovers."
She also said she would never forgive herself for not being there for him.
The couple - who also share a daughter, three, and son, seven - split in 2019, and both decided Bronson would live with his father.
She said she was consumed with "regret" and haunted by the vision of Bronson searching desperately for food and water. "I am in a living nightmare and I am never going to wake up from it," she said.
The little boy had been under children's services care, and Lincolnshire County Council confirmed Bronson would typically be seen at least once a month by social workers.
During the week before the father and son were found dead, Lincolnshire Police was contacted on two separate occasions by a council social worker who did not get an answer when they tried knocking on the door of Mr Battersby's home to see them.
The social worker communicated with Mr Battersby on 27 December and arranged to visit them on 2 January, but there was no response when they arrived at the door, a council spokesman confirmed.
The social worker "made inquiries at other addresses where the child could be" and contacted the police.
There was then a second unannounced visit on 4 January which also went unanswered, and Lincolnshire Police were contacted again.
On 9 January, the social worker was let into the property by the landlord, where the bodies of Mr Battersby and his son were found.
In a statement, the Independent Office for Police Conduct's (IOPC) regional director Derrick Campbell said: "The harrowing circumstances in which Kenneth and Bronson Battersby died are truly shocking. Our sympathies go out to everyone affected by their sad deaths.
"It is appropriate we carry out an independent investigation to consider the police response to any prior welfare concerns that were raised. We will be examining whether there were any missed opportunities by police to check on Mr Battersby and Bronson sooner.
"We will be in contact with Bronson's mother and Mr Battersby's family in due course to explain our role and how our investigation will progress."