I believe the killer of Valerie Percy was Frederick James Malchow.
His own gang fingered him. He admitted to investigators he had cased the Percy house on a trip to Chicago.
http://i296.photobucket.com/albums/mm176/pleasestandby2/malchow%20inter_zps0do6uwg0.jpg
The MO used in his burglaries was the same as the Percy burglary. He was a burglar. He was a serial rapist. When he escaped from the Outagamie County jail while he was being investigated for burglaries there, where did he end up? Buffalo, New York, where he was arrested at his mother's house. When he again escaped from jail the second time, he was there for two rapes and burglaries in Wynnewood, PA; one the daughter of a prominent family. This is when he met his end off the railroad trestle in June of 1967 with part of one of the handcuffs still attached to his wrist and his chest caved in. A fitting end for a monster.
Two interesting points never brought up on this forum:
1) Frederick Malchow was arrested in Buffalo, NY for rape
August 11, 1950, when he was only 23 years old. He had driven three juveniles to Hamburg, NY where he bound, gagged and raped them. So, obviously, he's a serial rapist.
http://i296.photobucket.com/albums/mm176/pleasestandby2/malchow_zpsg2gphqp0.jpg
2) When he escaped from the Outagamie County jail in 1961, one of the escapees was Gordon Rusch. Gordon Rusch was from Black Creek, WI, 15 miles north of Appleton, WI, in Winnebago County. Rusch instigated the jail break by having a Huber Law prisoner slip some hack saw blades under his cell door.
On Wednesday, December 18, 1963, Florence C. Kilsdonk, of Route 1, Black Creek, was found stabbed eight times in the chest, throat and back of neck with jugular vein slashed (ultimate cause of death), wrist slashed and bludgeoned about head. Found at 2:30 pm,, she had been dead about 8 hours. Definitely overkill. $200.00 still nearby on dresser, untaken. Weapon never found. Her two month old baby unharmed on the table beside her. Murder still unsolved.
How well did Frederick Malchow know Gordon A. Rusch? Did he ever visit Rusch at his home? How close did Rusch live to Florence Kilsdonk at the time? Did Rusch know Kilsdonk? (Rusch years later was charged with attempted homicide in 1969 for shooting his estranged wife in the back during a DD with their children present)
Whether Frederick Malchow was in Black Creek, WI when Florence Kilsdonk was murdered is unknown. The way she was killed is very similar to Percy's.
Another inmate said Hohimer told him Malchow and he killed Valerie
http://i296.photobucket.com/albums/mm176/pleasestandby2/hohimerconf_zpsivjmn8co.jpg