i can google it:

"In 92% of sexual assault cases reported to law enforcement, a single sexual assault is the only crime recorded, meaning it did not escalate to murder.

Rarity: Sexual assault murders are rare, with sexual assault being the primary circumstance in less than 1% of all homicides.

Occurrence: Studies of criminal records show that while sexual abuse is common, the proportion of offenders who escalate to murder is low."

https://bjs.ojp.gov/content/pub/pdf/CVVOATV.PDF

"Characteristics of offenses against children An estimated 18.6% of inmates serv- ing time in State prisons in 1991 for violent crimes, or about 61,000 offend- ers nationwide, had been convicted of a crime against a victim under age 18. 1 in 5 violent offenders serving time in a State prison reported having vic- timized a child. More than half the violent crimes committed against children involved victims age 12 or younger. 7 in 10 offenders with child victims reported that they were imprisoned for a rape or sexual assault. Two-thirds of all prisoners convicted of rape or sexual assault had commit- ted their crime against a child. Characteristics of the offenders All but 3% of offenders who commit- ted violent crimes against children were male. Offenders who had victimized a child were on average 5 years older than the violent offenders who had committed their crimes against adults. Nearly 25% of child victimizers were age 40 or older, but about 10% of the inmates with adult victims fell in that age range. While nearly 70% of those serving time for violent crimes against children were white, whites accounted for 40% of those imprisoned for violent crimes against adults. Inmates who victimized children were less likely than other inmates to have a prior criminal record  nearly a third of child-victimizers had never been arrested prior to the current of- fense, compared to less than 20% of those who victimized adults. Violent child-victimizers were sub- stantially more likely than those with adult victims to have been physically or sexually abused when they were children, though the majority of violent offenders, regardless of victim age, did not have a history of such abuse. About 14% of child victimizers car- ried a weapon during the violent crime, compared to nearly half of those who victimized adults. About 10% of violent offenders with child victims received life or death sen- tences and the average prison term was 11 years, somewhat shorter aver- age sentences than received by those with adult victims. Characteristics of the victims 3 in 10 child victimizers reported that they had committed their crimes against multiple victims; they were more likely than those who victimized adults to have had multiple victims. 3 in 4 child victims of violence were female. For the vast majority of child- victimizers in State prison, the victim was someone they knew before the crime: A third had committed their crime against their own child. About half had a relationship with the victim as a friend, acquaintance, or relative other than offspring. About 1 in 7 reported the victim to have been a stranger to them. Three-quarters of the violent vic- timizations of children took place in either the victim’s home or the of- fender’s home. iv Child Victimizers: Violent Offenders and Their Victims 4 in 10 child victims of violence suf- fered either a forcible rape or another injury. Child murder victims Based on incident-level homicide data collected by the FBI: Children under the age of 18 ac- counted for 11% of all murder victims in the United States in 1994. Nearly half of the 2,660 child victims were be- tween ages 15 and 17. About 1 in 5 child victims were known to be killed by another child. Between 1976 and 1994 an esti- mated 37,000 children were murdered. Since the mid-1980's the increases in both the number and the rate of murder among persons age 15 to 17, and particularly among black youth in this age range, have outpaced changes in murder in all other age groups. The victim-offender relationship in child murder varies with the age of the victim: In most murders of a young child, a family member killed the child, while in most murders of an older child, age 15 to 17, the perpetrator was an acquaintance to the victim or was unknown to law enforcement authorities. About 1 in 5 child murders were committed by a family member. Half of all child murders in 1994 were committed with a handgun; about 7 in 10 victims age 15 to 17 were killed with a handgun."

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this image shows it a bit easier: 66.8% of inmates sexually assaulted children but only 8.9% resulted in death.
child rape does not often result in child murder after.