The half-brother of a disabled Redditch man told an inquest he had not seen him in the four months before his remains were found in a suitcase at their home.
Daniel Kirby said his mother, Heather Wardle, had repeatedly told him James Hughes was in respite care before the pair were reported missing in April this year.
The decomposed remains of Mr Hughes were found in a suitcase in his back garden in Redditch, Worcestershire, less than 48 hours after his mother was found hanged in undergrowth.
An inquest in Stourport-on-Severn was told that police were alerted on April 19 after James's natural father, Paul Hughes, was fobbed off with "excuses" as to why he could not see his son from December 2007 until April this year, including a claim that he was on holiday in Weymouth.
James' half-brother Daniel Kirby, 18, told the hearing that he had not seen him since the latter part of 2007 and had believed his mother's claims that he was being given respite care.
Asked when he last saw his half-brother, he told the hearing it was probably in December, but added: "I can't remember the exact day or say an exact time. I just remember seeing him going into respite."
The warehouse worker also told the Deputy Coroner for Worcestershire, Margaret Barnard, he did not know how James's body came to be in the suitcase.
The 18-year-old, who lived with James and his parents, was advised by the coroner at the start of his testimony that he did not have to answer questions which might incriminate him.
Mrs Barnard said she found it difficult to understand how Mr Kirby had not noticed that the evenings and nights were quieter during the time he did not see James.
"You've got to live there to know what's going on," Mr Kirby replied.
The teenager also told the inquest he had not seen any suitcases at the family home and that he had asked his mother about James' whereabouts on several occasions. She used to tell me that he was on respite or at James's dad's when I used to ask about him.
"It would always be a different excuse every time I asked her," he said.
The witness added that he was hardly ever at home during the period in question and could not remember details of last Christmas. Recalling a conversation he had with his mother in January this year, Daniel said she had been struggling to sleep and was worried about money.
"She started saying she couldn't handle it no more and she was going to put him [James] in a care home."
Paul Hughes had told the hearing, which is expected to last for up to three days, that his former partner constantly made excuses as to why he could not visit James. He told the inquest he had last seen his son on December 28 last year, almost four months before his body was found.
Mr Hughes, who had always maintained regular contact with his son, said arrangements made to collect him for visits would get cancelled by Ms Wardle at the last minute.
On April 18, Mr Hughes, a managing director of a building firm, arranged to pick up James at Ms Wardle's house in Loxley Close, Redditch. He said he felt "chuffed" because he thought he was finally going to get to see his son.
But when he arrived, neither James nor Ms Wardle were home. Mr Hughes told
the court that he had taken Ms Wardle's claims that James was in respite care at face value and that he did not suspect that anything was going on until "the cat was out of the bag" on April 18.
"I had really missed him - he had been a massive part of my life," Mr Hughes added. The inquest heard that Ms Wardle's partner, Brian Kirby, told Mr Hughes on April 18 that he too was under the impression that James was due to be collected by his father and did not know where he was.
Brian Kirby called the police the following day, prompting a massive search.
James had the mental age of an 18-month-old child and suffered from epilepsy and needed regular medication. The suitcase containing his body was discovered near a barbecue table which had been covered with tarpaulin.
When forensic experts unzipped the black case, they found James' body wrapped in bed sheets. The only clothing visible was a nappy, the court heard.
The court was told that James suffered from Pica Disorder, a condition which caused him to eat non-food substances. He also suffered from a rare disorder known as Chromosome 22 Ring, which causes mental retardation, growth delay and a shortened life expectancy.
The inquest was told that death in early adulthood for sufferers was normal. It later emerged that James had not been seen by a GP since March 2005 but was still being provided with an epilepsy drug despite failing to attend appointments.
Dr Catherine McGregor, a GP based in Church Hill, said letters asking James to make an appointment to see a doctor were sent out in October 2006, January 2006, September 2007 and January 2008. But despite the fact that no appointments were made, he was prescribed medication until January 2008, although his final prescription was never collected.
Dr McGregor said it would have been "extremely risky" to have stopped James' medication, although she conceded that there was a "loophole" in the prescriptions system.
The coroner asked Dr McGregor: "Are you saying James Hughes slipped through the net?"
The doctor replied: "Yes."
The inquest also heard that a doctor who prescribed anti-depressants for Ms Wardle was unaware of claims that she was drinking a bottle of wine a day and using cannabis.
"We had no reason to worry about Heather Wardle," Dr McGregor said. "She had always been pleasant and co-operative."
The inquest will resume at 10am tomorrow.