Police in St. Louis said a recent spate of murders targeting sex workers could have been carried out by the same person, and the FBI was assisting with the investigation.
The bodies of a woman, a teenage girl and a man were discovered over the past two weeks.
Pam Abercrombie, 49, was found dead Sept. 16 on a north St. Louis sidewalk; Marney Haynes, 16, was found shot to death in St. Louis County on Sept. 13; and Casey Ross, 24, was found fatally shot Sunday in a vacant lot.
"Sex workers have been targeted and have either been shot or shot at by unknown suspects," St. Louis police said in a Sept. 17 statement.
Abercrombie's cousin, Tillonni Hamilton, said her relative was not a sex worker but a "hustler" who did odd jobs.
"We just want justice for my cousin and all the women that's been murdered," Hamilton told NBC affiliate KSDK in St. Louis.
The St. Louis chapter of Sex Workers Outreach Project tweeted Wednesday that the city had seen "an escalating pattern of robberies, assaults, shootings, and murders targeting sex workers."
"In our immediate orbit, this is something that a lot of folks are talking about and concerned about," Indigo Hann, co-founder of a sex work advocacy program MO Ho Justice Coalition, told KSDK.
Major Shawn Dace of the St. Louis Metropolitan Police Department said in news conference this week that there was some evidence to indicate the killings were committed by the same attacker or attackers.
Lt. Colonel Steve Sack of the St. Louis County Police Department said, "We're able to tie these incidents together."
Authorities said providing more details could jeopardize the investigation. The FBI did not respond Saturday to a request for comment.
Dace would not say whether authorities were looking for a serial killer.
"Until we finalize the investigation, we don’t want to categorize it as that right now," he said.