It was June 18. Businessman Ketan Vishal Agarwal had gone to Lohagad Fort near Lonavala with his fiancee Siya Goyal. It was meant to be a birthday outing for Siya, who was to turn 20 the next day.Ketan and Siya got engaged in February, and their wedding was scheduled for November. (HT)The first version of what happened came from Siya. She told police that Ketan slipped while taking photographs near the fort and fell into a valley.Police initially treated it as an accidental death. A report was registered, and the case appeared closed at the surface level.ALSO READ | Pune trek murder: The CCTV visuals that blew lid off businessman's killing by fiancee, her boyfriendBut, Ketan's family was not convinced. They said he was an experienced trekker who knew the terrain well and would not have lost balance so easily at that spot.That doubt changed everything.Family doubts that reopened the caseKetan’s family raised questions with investigators. They pointed out that he was familiar with Lohagad Fort and had trekked there before.Police then began a proper probe. They started checking CCTV footage, mobile location data, and the movements of everyone who was at the fort that day.The mistake that caught the killersOne of the first major breakthroughs came from CCTV footage at the foothills of Lohagad.Police noticed a person wearing a hoodie with the hood pulled over his head, along with headphones. Senior Police Inspector Dinesh Tayade and his team checked the local weather records for June 18 and found the temperature that morning was a hot 33 degrees Celsius.Investigators found the clothing choice suspicious and began tracking the person’s movement.That person was later identified as Chetan Chaudhary, Siya Goyal's lover.ALSO READ | How a hoodie in 33 degrees Pune heat helped police crack Ketan Agarwal murder“When we checked the June 18 temperature, it was 33 degrees Celsius that morning. During scrutiny of CCTV footage from the foothills, we noticed a person wearing a hoodie with his head covered and also wearing headphones. This raised suspicion because such clothing was unusual considering the weather conditions,” Tayade told HT.Police say this single detail helped them narrow down the suspect list and connect him to the scene.A phone left behindAs investigators followed Chetan’s movements, they discovered another unusual detail. Police say he had left his mobile phone at his residence in Kondhwa before going to Lohagad Fort. According to investigators, this appeared to be an attempt to avoid digital tracking.Despite this, CCTV footage and call detail records helped police reconstruct his movements.Soon, both Chetan and Siya were brought in for questioning.The 2,000 calls and an alleged planDuring the investigation, police found that Siya Goyal and Chetan Chaudhary had been in regular contact for months.ALSO READ | Who is Siya Goyal? Woman set to marry Pune businessman now accused of his murderAccording to officials, call records showed more than 2,000 phone calls exchanged between them, as per PTI. Investigators also said the two met at a cafe before the incident, where they allegedly discussed how and where an “accident” could be staged inside Lohagad Fort.The alleged sequence at Lohagad FortPolice reconstruction of events suggests that Chetan reached the fort before Ketan and Siya on June 18. Siya and Ketan arrived later.Investigators say the two accused then led Ketan towards an isolated area of the fort. It is here, police claim, that he was pushed into the valley.He died, after.The failed first attemptFour days before the incident, Ketan and Siya visited Lohagad Fort together. During that earlier trek, Ketan’s father later told police that his son felt someone push him from behind. He managed to save himself by holding onto nearby shrubs.Siya reportedly explained it away by saying she saw a snake and was trying to help him.ALSO READ | 'Was saving him from snake': Inside Siya Goyal's first Lohagad murder attempt that Ketan Agarwal survivedKetan reportedly asked his family about Siya's behaviour. He said she was always on her phone and mentioned a man named Chetan. Because the families knew each other through business circles, his father reassured him everything was fine."We thought about delaying the wedding because she was so young but her parents insisted that we go ahead with it as they would not find a match like my son," Ketan's father, Vishal Agarwal, told HT.Missing passport and cancelled Bali tripInvestigators also found another incident that raised suspicion.Ketan and Siya were scheduled to travel to Bali for a pre-wedding photoshoot. But the trip was cancelled at the Mumbai airport after Ketan’s passport went missing.Ketan’s family alleged that Siya may have taken the passport during a stop at Lonavala, which led to the cancellation of the trip.The hidden relationshipKetan and Siya got engaged in February. The wedding was scheduled for November, and preparations were already underway.The families had even booked a palace in Udaipur, with plans for a large ceremony worth ₹14 crore.During the investigation, police found that Siya and Chetan had been in a relationship for over a year, which Ketan’s family was not aware of.Both Siya Goyal and Chetan Chaudhary have been arrested and charged with murder and criminal conspiracy under the Bharatiya Nyaya Sanhita. They have been remanded to a seven-day police custody, as per PTI.Investigators say the case is still being probed.