Updated

The shooting death of a popular northern Virginia music teacher could be connected to two similar murders in the area over the last 10 years, authorities said Thursday, raising the possibility that a serial killer is at work in a quiet suburb of Washington.

Alexandria Police Chief Earl Cook told reporters during a news conference Thursday that forensic evidence indicates the three cases may be related, and they're now investigating the murders as a series of crimes, Fox affiliate WTTG reported.

Cook said a link is not confirmed and further investigation is still needed to learn if there is a definite connection, according to the station.

The announcement came four weeks after Ruthanne Lodato, a beloved piano teacher from Alexandria, Va., was shot and killed as she answered the front door of her home.

Authorities are probing whether Lodato's Feb. 6 murder is linked to the killings of Alexandria residents Nancy Dunning and Ron Kirby.

On Thursday, the Alexandria Police Department received forensic reports related to the three murders from the Commonwealth of Virginia’s Department of Forensic Science.

"Their analysis shows that the bullets recovered from the Lodato case exhibit the same general rifling class and characteristics and are similar in design to bullets submitted in both the Ron Kirby and Nancy Dunning cases," Alexandria police said in a statement on their website. "However, the results of the microscopic comparisons were inconclusive. It was not possible to identify or eliminate these bullets as having been fired from the same firearm."

"The similarities and unusual nature of all three shootings occurring in Alexandria require the Police Department to consider the possibility that all cases are linked together," the statement said.

Dunning, a realtor and wife of former Alexandria Sheriff Jim Dunning, was murdered on the morning of December 5, 2003, in her home. That morning, Dunning had shopped at the Target store at nearby Potomac Yards, WTTG reported. Police released photos from a security video of a man in the store whom they wanted to question, but he has never been identified.

Questions arose over whether the former sheriff may have been a suspect in his wife's death. He died in 2012.

Ron Kirby, a prominent transportation expert, was murdered in his Alexandria home on Nov. 11, 2013. Police said they believe the killing occurred in the morning on Veterans Day. Kirby, who was 69, had worked for decades on regional transportation issues for the Washington Metropolitan Council of Governments (COG). He was probably the foremost transportation expert in the D.C. region, according to the station.

Cook said evidence points to the Lodato case being connected to the murders of Ron Kirby and Nancy Dunning, also in Alexandria. He said the weapon used in all three cases seems to be similar in design, but that some of the comparisons of the bullets used in the three cases were inconclusive.

Cook said it appears that in all three cases, the victims presented themselves at their door, though it's not known if the suspect knocked or rang the doorbell in all three cases. All three murders occurred in late morning.

The suspect in the Lodato case is described as an older white male, with gray hair and a full beard. He was last seen wearing tan outerwear.

Anyone with information on the crimes is urged to call the Alexandria Police Department at 703-746-6864 or email crimetips@alexandriva.gov.

Click for more on this story from MyFoxDC.com

FoxNews.com's Cristina Corbin contributed to this report.