A Philadelphia doctor has been found guilty of the murders of three babies born alive and killed with scissors after late-term abortions.
Dr Kermit Gosnell, 72, was acquitted on another charge of killing a fourth baby, who let out a whimper before he cut its neck, prosecutors said.
But he was found guilty of involuntary manslaughter of an adult patient who died of an overdose.
The case became a flashpoint in the US debate over abortion.
Prosecutors are seeking the death penalty for Gosnell.
'House of horrors'
Former staff members of the clinic testified that Gosnell had routinely performed illegal late-term abortions past Pennsylvania's 24-week limit, delivering babies alive then using scissors to sever their spines.
Prosecutors argued that Gosnell had run a filthy, out-of-date "house of horrors" with unqualified staff - including the ones that administered a lethal dose of sedative drugs to 41-year-old Karnamaya Mongar, a refugee from Nepal.
Defence lawyers had argued it was the result of unforeseen complications.
Prosecutor Ed Cameron said to Gosnell during closing arguments in the six-week trial: "Are you human?
"To med these women up and stick knives in the backs of babies?"
Are you human?"
The jury was earlier deadlocked on two counts against Gosnell, but did not specify which of the multiple counts.
After the verdict was read on Monday, Gosnell appeared calm, the Associated Press news agency reports.
The jury will return next week to begin to hear evidence on whether Gosnell should get the death penalty.
The gruesome trial became a cudgel for those on both sides of the deeply divisive abortion debate in the US.
Anti-choice advocates argued that the case exposed the true nature of abortion.
But pro-choice groups said it showed what would happen if abortion regulations were tightened, driving desperate women to unregulated backstreet clinics.
Midway through the six-week trial, anti-abortion activists accused the US media of ignoring the case because of liberal bias.
The case also proved a scandal for Pennsylvania health authorities.
Officials had failed to conduct routine inspections of all of its abortion clinics for 15 years by the time Gosnell's operation was raided and closed down.
In the wake of the raid, two top state health department officials were fired, and Pennsylvania imposed tougher rules for clinics.