Homicide investigators are examining the killings of 15 prostitutes in eastern Harris County to see if they are linked to Crosby security guard Steven Alexander Hobbs, whom they charged Thursday with murder in the death of a woman found near his home.

The murder charge, dating from 2002, brought to six the number of prostitutes he allegedly killed or sexually assaulted in east Harris County. Investigators say they are looking into crimes committed as far back as 1996 and will eventually widen their inquiry into unsolved cases outside that area.

"Steven Hobbs is a predator, and he's been a predator for at least a decade," said Lt. Rolf Nelson, commander of the sheriff office's homicide division.

Hobbs was charged Thursday in the death of Patricia Ann Pyatt, 38, who was last seen walking from her Crosby home. Her remains were found Nov. 19, 2002, beneath the old Beaumont Highway bridge. She had been strangled.

He was also charged Thursday with the aggravated sexual assault of a prostitute that occurred several months before Pyatt's death, in August 2002.

A prosecutor said Hobbs hired the woman to perform oral sex, but instead he raped her, beat and violently choked her.

On Monday, the 40-year-old Hobbs was charged with capital murder in the death of Sarah Annette Sanford, 48, whose body was found nude and handcuffed in a wooded area near Crosby in October 2010.

To plead not guilty

Defense attorney Allen Isbell has said Hobbs will plead not guilty to the capital murder charges, adding he is eager to examine the DNA tests that allegedly link him to two murders.

Hobbs was arrested earlier this month by Pasadena police detectives, who charged him with kidnapping and sexual assaults against three female prostitutes. He is a person of interest in the death of Wanda Trombley, a 57-year-old prostitute whose skeletal remains were found dumped in Pasadena on Sept. 22.

DNA gathered from the remains of Pyatt and Sanford came back to the same unidentified person, Nelson said.

A major break in the case came when investigators visited where Trombley's body was discovered. That location was next to a job site manned by security guards.

Investigators knew from surviving victims their attacker was a very large, tall, red-headed white man who wore a uniform. The owner of the firm that provided the guards at the site supplied photos of male employees to investigators. Victims picked Hobbs out of a photo lineup.

Hobbs and other security guards voluntarily provided a DNA sample. On Oct. 13 the Harris County Institute of Forensic Sciences matched Hobbs to the biological material left at the scene of the murder of Sanford and Pyatt, Nelson said.

Large, red-headed man

After Pyatt's killing and the sexual assault in 2002, Nelson said investigators learned the suspect was a large, red-headed man. But they had little to go on other than a description, and Hobbs did not have a criminal record.

However, sheriff officials acknowledged Hobbs had been booked into the Harris County jail in 2000 after he failed to appear for a summons on a traffic ticket. But due to the minor nature of the crime, a DNA sample was not collected at that time.

Serial killer profile

Nelson said Hobbs fits the profile of a serial killer, noting there were no connections between his alleged victims other than their occupation as prostitutes and the circles they ran in east Harris County.

Nelson said his office has released an alert to every law enforcement agency in Southeast Texas with information about the two killings Hobbs is accused of committing, as well as attacks on prostitutes so they can examine their unsolved cases.

Assistant District Attorney Katherine McDaniel, who is prosecuting the cases, acknowledged the prostitute Hobbs is charged with assaulting in 2002 agreed to have sex with him.

"The woman in that case consented, for money, to perform oral sex on Mr. Hobbs," McDaniel said. "However, he choked her, he beat her and he almost killed her while he anally raped her."

Nelson said it did not matter to investigators that most victims were prostitutes, but that increased the difficulty of investigating the attacks.

"A lot of time, because of the business they're in, prostitutes are a little reluctant to deal with the police or to report sexual assaults," Nelson said.

Hobbs' attorneys have said their client is a hard-working family man who graduated from college, and the allegations against him have shocked his family.

james.pinkerton@chron.com