After 14-year-old Keira Gross was murdered in Berlin, the far right pounced. They spread rumours and misinformation online, blaming the crime on a Muslim immigrant from Chechnya who they dubbed “The Beast of the Caucasus”. One key activist, Lutz Bachmann of the anti-Islam group Pegida, even identified a boy who he said was the murderer, and posted his details with a link to his Facebook profile.

However, there was a problem: the rumours were wrong. It emerged that Keira was not murdered by a Muslim immigrant, but rather by a churchgoing German classmate who was obsessed with Batman’s nemesis, the Joker.

We hear from Keira’s mother about the impact the rumours have had on her life, and find out how extremists twist reports of crime to serve their political goals.

Presenter: Mike Wendling

(Photo: Keira Gross. Credit: Karin Gross)

Carrie Goldberg’s life changed when an ex-boyfriend threatened to post naked pictures and videos of her online. She was already practicing as a lawyer, but quit her job to start her own firm and give her clients - as she puts it - “the lawyer I needed when I was going through hell.”

When she began in 2014, there were few laws against what is now known as “revenge porn” – the non-consensual sharing of explicit photos online. Now many countries and US states have passed anti-revenge porn laws. Movements like #MeToo have also focused attention on sexual consent and harassment.

Carrie Goldberg tells BBC Trending how she has won legal victories for her clients. And she explains why social media and dating apps are both part of the solution and part of the problem.

Presenter: Mike Wendling

(Photo: Carrie Goldberg in her New York office / Credit: BBC Copyright)

Caroline Calloway built a huge audience on Instagram by posting fairy tale pictures of life as a university student in England, mixing romance and adventure with a dash of personal revelation and grit. But she recently found herself on the receiving end of a wave of abuse after she cancelled a tour of “creativity workshops”. It’s prompted a discussion about influencers – social media stars who have a lot of cultural clout and can often make a lot of money. But what happens when they let down their fans?

Reporter: Anisa Subedar

(Photo: Caroline Calloway. Credit: Instagram/Caroline Calloway)

In June 2017 more than 70 children arrived at a university campus in Indiana, US. They were there to take part in a nutrition study that examined the effects of diet and sodium reduction on blood pressure and cholesterol in adolescents. But the experiment swiftly came to a halt when a video was posted online of what was going on at the Camp. As a result, the multi-million dollar nutrition study was terminated.

We travel to the US to speak to the children who participated in the study, their parents, and a camp manager.

Reporter: Camila Ruz

(Photo: Purdue University Student Dormitory Building. Credit: Getty Images)

At the start of October some users of a music-streaming platform found that their accounts were playing songs against their wishes. Artists like the Bergenulo Five and DJ Bruej were streamed thousands of times, with Spotify users claiming the music was forced onto them.

Reporter: Jonathan Griffin

(Photo: A woman with an unhappy expression wearing headphones whilst placing her hands over her ears. Credit: Getty Images)

We meet investigators looking into social media manipulation and the people behind the Hamilton 68 project, which monitors suspected Russian accounts. Two reports recently prepared for US Senate investigators detailed extensive Russian efforts to influence major social networks.

Trending travels to Texas to meet the people behind one of the reports at New Knowledge, a company that was involved in the development of the “Hamilton 68 dashboard” – a running tally of hashtags and other information on accounts linked to Russian propaganda.

New Knowledge has been one of a number of companies at the forefront of the investigation into the Kremlin-linked Internet Research Agency and other disinformation campaigns. But the firm has also been criticised for lack of transparency around Hamilton 68 and for its involvement in a project during the US Senate race in Alabama.

How do researchers answer those criticisms – and what are the methods they use to establish the origins of disinformation and social media propaganda?

Presenter: Anisa Subedar

Image Caption: New Knowledge co-founders Ryan Fox (left) and Jonathon Morgan (right) at the company’s offices in Austin, Texas

Russian pensions, football in Africa, jihadi propaganda – these are among the stories, trends, and conversations that are to shape social media in 2019.

To find out more, Marco Silva talks to BBC colleagues who watch social media around the world. What stories and conversations will they be following online in the year ahead?

Presenter: Marco Silva

Photo caption: a man holds a smartphone with the icons for various social networking apps seen on the screen.

A look at BBC Trending’s highlights from the past year of covering social media. From America’s student anti-gun movement to the continuing noise made by #MeToo activists, social media played a huge role in some of the biggest political movements of the year. And of course the World Cup was drenched in tweets and hashtags - plus, we visit the gaming team with an average age of 67. All that and more, in our roundup of the year on social media as seen by BBC Trending.

Presenter: Mike Wendling

Photo Caption: A hashtag in a speech bubble

YouTube has deleted thousands of videos after a BBC Trending investigation. Seven months after we initially broke the story of essay-writing services advertised by top YouTubers, we found that the problem is bigger than ever, and academic cheating companies like EduBirdie have now moved on to other platforms like Snapchat, Facebook and Google.

Presenter: Anisa Subedar

Photo Caption: A YouTuber advertising the EduBirdie essay-writing service

Instagram’s search function does not always shield people at risk of eating disorders from seeing potentially harmful posts.

A Trending investigation has found that although the site has filters in place to make the most obvious eating disorder-related hashtags unsearchable, misspellings allow people to navigate around the restrictions.

And health warnings do not always pop up when users type in search terms that could lead them to some very extreme content.

We hear from people who have suffered from eating disorders who describe the kinds of things they have seen on Instagram, and tell us of the challenges of using a social network as part of the recovery process.

Instagram acknowledges the complexity of the issue and says it is dedicated to keeping harmful content away from vulnerable users. And as a result of our research, the Facebook-owned company has made some adjustments to try to further protect users.

Presenter: Anisa Subedar

(Photo: A photo of a pizza being taken on a smartphone. Credit: Getty Images)