Video report by ITV News correspondent Ivor Bennett
A man arrested over the disappearance of Hertfordshire University student Joy Morgan was questioned on suspicion of murder, police have confirmed.
The 40-year old from London was released under investigation while inquiries continue.
Joy was last seen on Boxing Day at a Christmas celebration at her church in Ilford, east London and made WhatsApp contact with classmates the following day.
She was reported missing on February 7.
Video footage of her dancing with friends at the church event has been released by Hertfordshire Police.
Speaking to ITV London following her daughter's 21st birthday on Tuesday, Joy's mother Carol Morgan said: "I should be able to say happy birthday to her.
"I should be able to say hello to her and I wasn't able to for the first time in 21 years.
"Somewhere, there's something not right.
"I don't know what it is.
"I don't want to think the worst...
"I want my baby back, okay, I need my baby back, I need to see my baby, I need to see my Joy."
Detective Chief Superintendent Karena Thomas appealed to the public for any more information about the trainee midwife's whereabouts.
She described Ms Morgan as a "focused and determined" student and said he disappearance was "completely out of character".
Ms Thomas added: "At this stage we have to consider she may have come to harm."
The officer described the investigation as "complex" and said: "To gather a full picture of Joy's life is a difficult jigsaw to piece together."
Police are particularly interested in hearing from anybody who may have seen the student in a distinctive red and black Honda car that she regularly took lifts in.
Ms Morgan has links to Ilford, Battersea and Cricklewood in London, as well as Bedfordshire.
She is described as slim, around 5'5" tall, with Afro hair that she regularly covers with a scarf, and glasses.
On the arrest and investigation, Carol Morgan said: "Police said they arrested someone and they were talking to him, they kept him, then he's been released, that's it.
"I don't know who he was, what association he had with her, I don't know anything.
"All I know is that from December 27, 2018, I and the police know no one has seen her."
Her brother Earl told ITV News how he thinks about his sister's disappearance every day.
He said: "You wake up thinking about it, go to bed thinking about it, eat thinking about it, you want to have a clear mind and have an optimistic mind but it's hard."
Her family issued an appeal earlier this week as they marked her birthday without her.
In a statement they said: "We love you, we miss you.
"Wherever you are, text or call so that we know you are alright.
"It doesn't matter what has happened.
"Just come home."