The family of a 16-year-old boy murdered in east London on Tuesday have expressed concern about how the police dealt with the case, and have claimed that information passed on was not followed up properly.

The death of Shanur Ahmed is the 18th homicide recorded so far this year in London. The teenager was found with head injuries on scrubland near Gallions Reach DLR station just after 8.30am on Tuesday.

Detectives are trying to find a motive for the killing, and among the lines of inquiry they are are examining is whether the brutal attack was gang-related. Police were called on Monday evening to a report of a group of youths, some armed with baseball bats, fighting near Gallions Reach.

On Thursday, eight bunches of flowers and some daffodils tied together with elastic bands were laid on grass beside the station, near where Ahmed’s body was discovered.

Asad Ahmed, the teenager’s uncle, said: “When Shanur was reported missing on Monday evening, after that we had some information via his friend on Snapchat to say his life was in danger. This message was forwarded onto officers who came to take the initial report but it was not followed up appropriately.”

A Metropolitan police spokesperson said the force’s directorate of professional standards was looking into the issue of the call from the family. They added the matter had also been passed to the Independent Office of Police Conduct “as a matter of course”.

Information about Shanur that had been circulating on social media has since been removed.

Asad Ahmed said that the officers handling the case may have been inexperienced, and said the family had not yet made a formal complaint to the Metropolitan police, although it had been mentioned informally.

“It was just that level of expertise lacking at that time and it needs to be flagged. We have flagged it with the local police – whether it’s a training issue within the police [or something else], it needs to be looked into. The pressure needs to be there from the family and the public, because there cannot be another life lost through an incident like this,” he said.

The uncle said that the family, who live in Manor Park, tried to locate Shanur themselves. They drove past Gallions Reach station three times – where a witness had seen the youths with baseball bats – but they did not realise the teenager lay yards away in the scrubland.

Ahmed said that his nephew’s glasses were also found by the family on the site where his body was discovered. “To find they were still at the scene was a distressing moment [for the family],” he said.

Police are trying to establish what the relationship was between the victim and the group of around 30 males seen fighting. Another line of inquiry is whether he was involved in that group, or somehow became caught up in it. Detectives are cautious about automatically assuming that the reports of a group of 30 males in the area the day before definitely link them to the death.

“We haven’t been given further information as of yet,” Ahmed said. “We are hoping for more information so his parents will be able to see their child. They have not been able to see his body yet.”

The uncle described his nephew as a “very caring child” who wanted to help others all the time. “He was very popular among his friends in college and school. He was the child that every mother and father would like – very helpful, an ideal child.” He added that he did not think his nephew was involved in any gangs but was in “the wrong place at the wrong time”.

Before he was killed, the 16-year-old had visited a friend in hospital who had been involved in a fight. “There was a fight outside college, that is what we have heard,” Ahmed said. “I am not sure what it was relating to … We don’t know the detail of it at this stage but believe there are hundreds of hours [of] CCTV footage going through.”

Shanur vanished at 6pm after the hospital visit. “He was ambitious, studying his A-levels. He wanted to go to university and to help his dad with his business, learn how to drive,” Asad Ahmed said.

“He has got a younger brother who is 10 years old and yesterday was very stressful. He came over and asked – can they resuscitate him [Shanur] and bring him back? How do you explain to a child that the brother they love and was always with is no more?”

On Wednesday, DCI Larry Smith said: “A young teenage boy has died and his family and friends are devastated. They want answers and they deserve all the help the public can give them.”