A killer concealed his girlfriend's body under the sitting room floorboards before constructing a "cunning and clever" charade to cover his tracks, a court has heard.
Stephen Devesey is alleged to have murdered 18-year-old Nicole Cartmell almost three weeks before her decomposing body was found at his terraced home in Handsworth, Birmingham.
Opening the case against Devesey to a jury at Birmingham Crown Court, prosecutor Timothy Barnes QC claimed the 21-year-old had repeatedly lied to police, Miss Cartmell's mother and other people about her whereabouts.
Alleging that Devesey killed Miss Cartmell by asphyxiating her shortly after she made a "frightened" 999 call on February 10 last year, Mr Barnes told the court: "What caused him to kill her on that day we do not know.
"When he had killed her, the defendant prised up some floorboards in the front room of his address and dropped the body into the cellar some 7ft below.
"He covered the body with layers of clothing and rubbish and there over successive weeks the body decomposed, giving rise to unpleasant smells which the defendant tried to mask with the aid of incense sticks."
At the start of what is expected to be a two-week trial, jurors also heard allegations that Devesey used the victim's bank card on four occasions between her death and the discovery of her body at his home in Whateley Road on March 2 last year.
Devesey is also said to have flirted with a woman he met on Facebook in the days after the alleged murder, changing his relationship status from "engaged" to "it's complicated".
Urging the jury to consider the "persistent lies" told by Devesey to distance himself from the fact of Miss Cartmell's death, Mr Barnes said: "The Crown say he acted from the outset in a calculating and devious manner designed to allay the suspicions of those who wanted to know where Nicky was, and concerned to cover up the enormity of what he himself had done."
Following Miss Cartmell's apparent disappearance, the court heard, Devesey sent a text message to her mother to make it look as if he was trying to contact the teenager.
Mr Barnes told the jury: "He said he would go and look for her in West Bromwich.
"Of course it was all a charade. Quite a cunning and elaborate charade."
After his initial arrest on suspicion of fraud in relation to the bank withdrawals, a search of Devesey's housing association property led to the discovery of Miss Cartmell's purse, driving licence, and a coat she was seen wearing.
Devesey was then arrested on suspicion of murder and made no comment in police interviews after initially being taken to a psychiatric unit.
Devesey, who denies murdering Miss Cartmell on a day between February 10 and March 2 last year, had contact with social workers and housing officials in the weeks after he allegedly killed her.
During a conversation with a housing official, the defendant demanded a smaller property because his girlfriend had finished with him, jurors heard.
Miss Cartmell, who was reported missing by her family on February 14, was living with her mother when she disappeared after disagreements with her boyfriend.
During his opening speech, Mr Barnes said the jury would have to consider three issues in the case - whether the defendant was responsible for killing Miss Cartmell, if he intended to kill her or cause her serious bodily harm, and whether he was suffering from diminished responsibility at the time.