© YouTubeTargeted? The shooter walked up to Gelareh Bagherzadeh's car and shot her in the head at close range
  • He [ex-boyfriend] heard a loud thud - doesn't recall hearing any gunshots, but a loud thud - and then a screeching noise. He said it sounded like someone driving away'
  • They received two calls about gunshots in the area within 45 minutes
Detectives investigating the murder of an Iranian molecular scientist gunned down in her car as she drove home believe she was followed or that someone was waiting for her.

Gelareh Bagherzadeh, 30, who lobbied on behalf of Iranian women's civil rights, was struck by a single bullet that entered the passenger door window as she talked on her cell phone with her ex-boyfriend.

Her car then rolled into and a garage door yards from her parents' home in a townhouse community just southwest of Houston, Texas.

The car's engine was still running when police found her body behind the wheel about 12:30am on Monday.

According to police, someone walked to the passenger's side of her car and shot her at point-blank range.

Describing what the ex-boyfriend heard, homicide Sgt. Richard Bolton told KHOU-TV: 'He heard a loud thud - doesn't recall hearing any gunshots, but a loud thud - and then a screeching noise. He said it sounded like someone driving away.'

Sgt Bolton said police have questioned the ex-boyfriend but he is not a person of interest in the case.

Bagherzadeh was a molecular genetic technology student at M.D. Anderson Cancer Center in Houston. She also was active in promoting Iranian women's rights, police spokesman Victor Senties said.

'It appears she was one of the ones who would be out protesting, and she was very well known in the Iranian women's rights community because she was constantly out protesting,' he told the Houston Chronicle.

Senties said it was unclear whether her death was related to her background or her activities.

It was a neighbour, who heard the sound of the shattering glass, who first alerted the police.

Officer J.C. Padilla said: 'When the officer arrived, the car's tires were still spinning. He had to reach in and turn off the motor.'

Authorities received two calls within the space of 45 minutes about gunshots in the area. It is not known if they are linked.

Police are offering a $5,000 reward to anyone who knows any information.

Investigators at the Houston Police Department are currently searching through the video footage from a neighbour's surveillance system in an attempt to find clues as to what happened.

Locals and community members are stunned that such a violent crime could have taken place in the neighbourhood, where, according to one resident Oguz Orhov, 'you don't even hear the traffic.'

Sherise Mousa, who heard the gunshot and lives in the low crime area, told Fox News: 'It's scary because I live over here and I'm a single mom.'

Sgt Padilla added that Woodway Point is not a place the police are often called to.

Ms Bagherzadeh was one of the founding members of of Sabz Houston, a local Iranian organization that urges change in the current Iranian government. Her friends describe her as sweet and smart.

The group is made up of about 30 people - mostly students - who protest peacefully for freedom and change in the government.

She appeared in an online video filmed by the Houston Chronicle in 2010 for her participation in a series of protests against the Ahmadinejad government. During the interview, she, like many other protesters, refrained from using her last name for fear of persecution.

'At the moment, our investigators are trying to confirm whether she was followed,' HPD spokesperson Victor Senties told CultureMap, noting that it remained unclear whether her protest background played a role in the murder.