The bodies of two minor siblings who were kidnapped from their school in East Delhi's Mandawali were found near a railway track in central Delhi on Saturday.

The siblings, identified as Yashbi and Mansij, were reported missing on 26 February. Their bodies were found in a decomposed state and were identified by their school uniform.

According to the police, the brother-sister duo were abducted for a ransom of ₹30 lakh and their parents had received many phone calls to hand the money to the kidnappers in return for their release.

"On reaching the school, she learnt that some men who posed as relatives took her children away in a car. From that evening till Thursday, the parents received about ten calls for ransom that increased from ₹20 lakh to ₹30 lakh," Deccan Herald reported a police officer as saying.

Delhi police have detained three, including the children's uncle in connection to the incident. Authorities said on Sunday that the murder was plotted by their maternal uncle Amit Singh who was in a need of money to invest in a real-estate business.

Narrating the chain of incidents that led to their deaths, Deputy Commissioner of Police Prabhakar told CNN-IBN, "They tried to kill the children in Millenium Park when they did not get the ransom and then went to Pragati Maidan-Bhairon Marg crossing. They first killed the girl and then the boy."

Further investigation revealed that the accused strangled the children to death and used a rock to crush their bodies. The corpses were left in the open to be eaten by strays, reported NDTV. 

Police will indict the charges of kidnapping, murder and destruction of evidence against the accused.

"We knew that some relative was involved, our prime objective was to rescue the kids but it's unfortunate that we couldn't," the police said in a press conference.

"After analysing the calls, we realised that the kidnappers were insiders. We wanted to save the children. Hence we did not take any drastic action. We knew that Amit Singh had recently rented a flat behind the family. We picked him up first and he confessed."