Detectives fear that the man, who frequently uses a knife to terrorise his targets, will strike again soon.
In a large number of the cases, he has grabbed his victim from behind, often from a bus stop, or off the street, and taken her to a quiet spot before attacking and robbing her. Some of the women have suffered serious sexual assault and are deeply traumatised.
He is believed to be responsible for at least 18 separate attacks in Birmingham and in Kidderminster, in Hereford and Worcester. The youngest victims were 15 years old.
A team of 40 officers is trying to track down the serial criminal and a reward of pounds 1,000 has been offered. Detective Chief Inspector Trevor Swingler, who is heading Operation Blackpool, said: "We need to catch this man before he attacks anybody else."
The attacker often uses a craft knife with a retractable blade during the assaults.
A police spokesman said: "He frequently approaches people from behind with a knife and puts his hands over their mouths and then attacks them."
The first attack is believed to have taken place on the evening of 2 December, when a 16-year-old girl was grabbed from behind by a man while she was walking along the road in Harborne, Birmingham, and was dragged into a park where she was indecently assaulted.
Other victims include a girl aged 17 who was approached by a man with a knife while she was waiting in a bus shelter in Solihull on 28 December. She was forced into the shelter and sexually assaulted before having her money snatched.
In one evening, on 18 January, in Kidderminster, five women were attacked at knifepoint. They included a 40-year-old who was indecently assaulted and an 18-year-old who was cut on the hand.
On 19 January, the attacker ran up behind a woman aged 19 at Bartley Green, Birmingham, and forced her on to nearby grassland where she was robbed and indecently assaulted.
Two girls were threatened by a man with a craft knife on 20 January while they were walking in Northfield, Birmingham. The man forced them into an alley and then indecently assaulted them, before fleeing.
Two 15-year-old girls were assaulted by a knifeman while waiting at a bus shelter in Weoley Castle, Birmingham. They were pushed to the ground and threatened. However, the attacker was disturbed by a motorist and ran off.
A 16-year-old walking in Northfield was threatened and forced behind a block of maisonettes where she was indecently assaulted and robbed on 19 February.
Two days later a 15-year-old girl was seized and threatened with a knife while she was waiting at a bus stop in Solihull. She was robbed and indecently assaulted.
The last reported incident happened on 2 March when a 17-year-old girl, walking home in Bournville, Birmingham, was forced into a nearby park at knifepoint and sexually assaulted and robbed.
The attacker is usually described as a white man, between 5ft 6in and 5ft 10in, aged in his late twenties or early thirties, of stocky build, and wearing a baseball cap, a dark bomber jacket, jeans, and training shoes.
Anyone with information about the attacker should contact the West Midland police on 0121 626 4123.Reuse content