LONDON (AP) – Their naked corpses showed no signs of struggle, raising questions of whether a suspected serial killer may have drugged the five young women – all addicts and prostitutes – before killing them and dumping their bodies on the outskirts of an English port town.

“The fact that they were drug users will make the work more complicated” for forensic experts, said Sandra Graffham, a Suffolk police spokeswoman.

The fifth victim was identified Friday as Annette Nicholls, 29, but a coroner was unable to say what caused her death.

One woman died from asphyxiation and another died from what a coroner called “compression to the neck.” The causes of death for two others are still unclear because their bodies were found in water.

Forensic psychologists have asked whether the killer lured and then anesthetized the women with drugs. None of the bodies showed signs of significant trauma or sexual assault. However, it will take days to complete toxicology reports that could show whether the women had been drugged or the level of previous drug use, police said.

Experts from Britain’s equivalent of the FBI – the National Centre for Policing Excellence – were in Ipswich, a town about 70 miles northeast of London that used to be a bustling port in the 19th century. About 300 specialists have also been sent in.

Kevin Dominic Browne, who specializes in forensic psychology and whose center in Birmingham has studied serial killers, said the killer may have drugged his victims to ensure he had power over them.

He said often these types of killers have been abused themselves or suffered some type of trauma associated with sexual intimacy.

Serial killers usually enjoy the physical sensation of killing, preferring strangulation or bludgeoning to guns and other weapons, experts said.

“It may be this person gets a real charge out of playing God but doesn’t necessarily relish hearing the screams of his victims,” said James Alan Fox, a psychology professor at Northeastern University in Boston and author of several books on serial killers. “Drugging them would have also made it easier on him – psychologically – to abduct them, kill them and dispose of their bodies.”

“Some serial killers feel it is their self-appointed task to rid the streets of prostitutes and in a case like this, you wouldn’t necessarily see any sexual molestation,” Fox added. “It could also explain why he might have drugged them.”

All five victims were found over a 10-day span just miles apart in and around Ipswich.

Gemma Adams, 25, was the first woman to be found in a stream Dec. 2. She grew up in the Ipswich area and became hooked on heroin after leaving a job at an insurance company. Her boyfriend reported her missing on Nov. 15.

The naked body of 24-year-old Anneli Alderton was spotted in the woods Dec. 10, after initially being mistaken for a discarded mannequin. Police said it appeared she had been strangled.

The body of Tania Nicol, 19, was found in a pond. She was brought up in a poor section of town and was reported missing Nov. 1.

The body of Paula Clennell, 24, who told reporters days before her death that she was afraid but needed to return to the streets to support her heroin habit, was identified by police Thursday. Authorities said she died of “compression to the neck.”

Nicol’s family spoke emotionally of their daughter Friday, saying that her life had taken a downward spiral after the trainee beautician became hooked on heroin.

“Tania has been taken by someone who needs to be found,” said Tania’s father Jim Duell, who was flanked by her mother, Kerry Nicol. “Tania was a lovely daughter – she was a caring, loving, sensitive girl who would never hurt anyone.”

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