Warning: This article contains descriptions some readers may find upsetting

The pencil drawing of the long-haired, striking woman had been in their home for some time. But Sarah thought nothing of it. Her daughter Casey had been a talented artist and spent many hours absorbed in her art work.

It was only later that Sarah started to wonder about its significance and felt compelled to investigate. She soon found that Casey had posted it online. The caption next to it simply read: "The gorgeous woman is Teal Swan, a beloved spectacular spiritual guru."

Casey had taken her own life just a couple of months before. Sarah, devastated by the loss of her only daughter, wanted to try and understand more about her final weeks.

Who was this woman who had been such a subject of fascination for the 18-year-old?

Teal Swan is a self-declared spiritual teacher who calls herself a "personal transformation revolutionary" and "spiritual catalyst".

Born in Utah as Mary Teal Bosworth, she runs retreats in the US and Central America. She has hundreds of thousands of followers across social media - her YouTube channel has more than 79 million views.

Her brand centres on giving mental health advice, much of which is aimed at people who feel depressed, or suicidal. Swan, whose beliefs include reincarnation and the power of crystal healing, says her experience as a survivor of several suicide attempts gives her particular insight that she claims mental health professionals lack.

Swan says her intention is to help people who are in crisis and many people say her teachings have helped them when they were suicidal.

But Swan's critics accuse her of risking the glorification of death, and mental health experts that I spoke to called some of her approaches "irresponsible" and "dangerous".

Sarah sits in her living room in north-west US, Christian music playing softly in the background as sunlight streams through the windows.

She and her husband tell me about the call that shattered their world - the one in which they found out their daughter had taken her life.

Image copyright Katherine Lam

While Sarah knew Casey had been dealing with the pain of a recent break-up, she had no idea just how bad she had been feeling, or what she had been considering doing.

Sarah began trawling her daughter's social media accounts for clues.

She spotted that Casey had shared her pencil portrait on Facebook with the caption identifying it as Teal Swan, and soon realised her daughter had joined the "Teal Tribe" - a private Facebook group, which means only members can see what is in it.

Sarah joined the group and was horrified at what she discovered. She read a post by her daughter saying that she had tried to take her own life. The picture with the post was a stock image of a woman holding two fingers to her head like a gun.

In response, two people, including one of the volunteers that help moderate content in the group, replied with Swan's video entitled "I want to kill myself (What to do if you're suicidal)".

In the video Swan urges those who are feeling suicidal to seek medical help, but goes on to say that in her experience, for some people, this may not help long-term. She instead suggests that suicide be seen as "our safety net or our re-set button that's always available to us". She argues that viewing it in this way enables people to set the idea aside, and instead concentrate on what they can do to make themselves feel better in the present.

She also suggests an exercise in which viewers are told to lie down on the floor and imagine their deaths in "grisly detail". Swan argues in the video that by doing so viewers will realise that there is "nowhere to go but back to life… so why leave?"

She stresses in the video that killing oneself would "create a devastating ripple" for loved ones, and "it does matter if you are here or not here… You don't want to die. What you want is an end to your pain."

The video was among the top results in a Google search on terms related to suicide when we viewed it in early November.

Image copyright Katherine Lam

We do not know if Casey watched that video, and if she did do so, we cannot know how, if at all, it would have influenced her final fatal decision. But her posts shortly before she died do reflect some of the language that Swan herself uses, including references to rebirth.

Her mother Sarah is furious that posting the video was the only response from the Teal Tribe group to Casey's message, and that no-one called the police, or made any attempt to contact the family.

Just two weeks after Casey posted about her initial suicide attempt, she shot herself and died.

"What a huge missed opportunity and an incredible mistake," Sarah says.

"While I believe that there [was] more than one undercurrent happening in the life of our daughter, you would have to convince me otherwise that Teal's teachings did not play a significant role in the mind of our daughter when she took her life.

"It's almost like a rehearsal," Sarah says of the advice in the video.

To find out more, I joined the closed Teal Tribe Facebook group of more than 27,000 members and saw many posts that I found disturbing. There were repeated discussions of suicide, with people saying they wanted to end their lives, and group members offering advice.

Sometimes suicide prevention lines were given in response to posts. But many times, only Swan's video on what to do if you feel suicidal was posted, along with advice from other members.

During the weeks that I tracked the group, I found out that another young member of the forum had also taken their own life within days of posting about feeling suicidal.

Teaching in person

As well as teaching online, Swan hosts workshops in person across the US and Europe. Tickets cost up to $200. I went to one in Chicago, and met fans who clearly feel an intense connection with her.

One told me Swan is "changing the world". Another called her a "genius of human relationship connection and insight".

The event lasted for about six hours, with audience members being called up on stage, where Swan would give them advice. They talked about deeply personal issues, from abuse, to suicidal feelings. One man said he watched her videos for five hours every night.

I met Swan after the workshop, and asked how she would respond to those who accuse her of encouraging suicide.

At first she laughed at that idea, saying: "That's pretty funny. It's really funny to me."

If you look at the demographic of people who are interested in my type of material - you're working with an unstable group of people. Teal Swan

Then she took a more serious tone.

She said to call her a proponent of suicide was "ridiculous" and said that anyone who does so obviously hasn't watched her videos.

When I put it to her that two young people who were members of her group had taken their lives, the atmosphere grew tense.

"I am not aware of them," she answered.

She then grew visibly angry, saying that she was the reason more people hadn't killed themselves.

"If you look at the demographic of people who are interested in my type of material - you're working with an unstable group of people.

"[To suggest I am] responsible for suicide in people who came to me suicidal, that's pretty insane."

When it came to her Facebook group Swan admitted that she does feel a lot of anxiety.

"This is the worst part of my career," she told me.

"You start a Facebook group hoping that it's going to be a place for all these individuals to come to. Then let's say somebody does decide to kill themselves out of this large group of people who are already suffering before they get to you.

What you're doing when you tell somebody to visualise how they're going to kill themselves, is you're telling them to practise in their mind Dr Jonathan Singer

"I'm trying to get moderators who are on different time zones but let's say one of us doesn't see it [a suicidal post]. And now somebody says you should have seen it. Now it's your fault they committed suicide.

"We think about this all the time. You've got people who are vulnerable. What are you supposed to do when you can't catch all of it?"

But she also admitted that the volunteers who help run the page receive no training and few instructions on what to do if they do see posts in which someone says they feel suicidal.

"Sometimes it feels like you have a psych ward, with nobody tending the building and you can't afford to pay them to attend the building. And who's going to sign on for that type of a job anyways?"

I put it to her that perhaps social media is not the right forum for such sensitive discussions.

"That's actually my question I ask myself a lot [and] I think about my 15-year-old self," she says.

"I'm thinking about what I would have wanted when it was three o'clock in the morning and everybody else in my household was asleep.

"If there had been somebody on a YouTube video telling me how to feel differently I would have wanted that."

We will never know whether anyone who took their life was influenced by Swan's teachings. Indeed Swan maintains that people tell her all the time that she has helped them.

In a statement Swan told us that: "Suicide is never the answer. My teachings are designed to help people choose life. Any suicide is a tragedy, and we send our deepest condolences to this young woman's family."

She also added that "many mental health professionals support my teachings".

Since our interview Swan has released another video, making it "crystal clear" that she's against suicide, and that her intention is to help people, and certainly not to encourage the act. She says she is trying to de-stigmatise discussions around suicide.

And destigmatising the issue is something every mental health expert I spoke to during my investigation told me was needed.

Experts' concerns

But they all raised concerns about aspects of Swan's teachings.

One of those experts is Dr Jonathan Singer, the president of the American Association of Suicidology.

"When I heard Teal say that suicide can be a 're-set button' I was disturbed," he tells me.

"It suggests you can kill yourself and that things will start over again and be better, and that is not true."

"She's got these ideas that in her mind are only helpful. But for others could be really dangerous."

"What you're doing when you tell somebody to visualise how they're going to kill themselves, is you're telling them to practise in their mind," he says.

He explains that research shows this type of imagery rehearsal is "a very effective way of improving your actual ability to do something". For example, it is something that Olympic-level athletes use, he says.

"And so to tell somebody to think through how they're going to kill themselves, that's not safe."

I also spoke to Ged Flynn, the CEO of the UK suicide prevention charity Papyrus, and showed him Swan's video which advises viewers to imagine their deaths.

"It is not helpful in any circumstances to encourage anyone who has thoughts of suicide to imagine their being dead and further to glorify that state," he said. "This exercise can only lead to the risk of harm and even death. Such exercises are irresponsible. She is risking the glorification of suicide."

Swan argues this technique is about taking subconscious suicidal ideations, and consciously going to a different place with them - resulting in a more positive outcome.

Dr Singer is also concerned about where and how Swan's content is being shared.

He argues that while it can be helpful for people in similar situations to offer each other support, forums like Facebook can become "like an echo chamber".

"If you're suicidal and you go on a forum and everybody's posting about being suicidal, then it normalises being suicidal."

In Dr Singer's view, social media companies should do more to regulate content, and to help people reach out to people who may want to harm themselves.

He argues that their technology should be sufficiently developed at this stage to enable them to take action.

"I think they absolutely should intervene when people are suicidal."

In response to our investigation, Facebook has closed down the Teal Tribe closed forum, telling us that: "In consultation with suicide and self-harm prevention experts, our policies allow some content which expresses an intention towards suicide or self-harm as an opportunity for someone to respond to what may be a cry for help. However, we do not allow content which directly promotes or encourages suicide or self-harm."

However some of the members have set up a new Facebook group called "Phoenix Tribe." While it is not administered by Teal Swan, at least one senior person from her management team is a member, and already I have seen people talking about feeling suicidal, with no helplines offered from other members.

YouTube told us that they "strive to strike a balance between prohibiting videos that encourage dangerous acts, while also offering a place where people can talk openly and honestly about their thoughts and experiences".

They said the video in which Swan suggests that the viewer imagines their own death has now been removed for violating their policies. But it is still up on at least one other person's channel, and has been shared within the new Facebook group.

Image copyright Katherine Lam

In their quiet suburban home in north-west US, a mother and a father are still struggling to come to terms with the death of their daughter.

My conversation with Sarah and her husband has stretched from afternoon to the evening, as they share how their family has been changed forever.

They no longer have a home phone, so strong was its association with the devastating call that changed their lives.

Sarah says she hopes that in sharing their story, they can help someone else.

"Life is precious. Life is a gift. Life doesn't come with a reset button.

"And if you're feeling vulnerable, [a] video is not the authority on a topic of this nature.

"Go talk to your pastor, [or] someone who loves you, someone who cares about you. That's your authority on a topic of this nature."

Additional reporting: Joanne Whalley

Some names have been changed

Getting help

Canada and US:

From Canada or US: If you're in an emergency, please call 911

In the US, you can call the National Suicide Prevention Lifeline on 1-800-273-8255 (TALK), or the Crisis Test Line by texting HOME to 741741, or visit SpeakingOfSuicide.

Young people in need of help can call Kids Help Phone on 1-800-668-6868

UK:

If you are in the UK, you can call the Samaritans on 116123

BBC Action Line has support and more information on emotional distress