How was much money stolen the night of Karen's and Anethe's murder?

I will assume this question pertains to the so-called Smuttynose Murders, which took place on Smuttynose Island (off the coast of New Hampshire) in 1973.
On this evening, three women—Maren Hontvet, Karen Christensen (who were sisters), and their sister-in-law Anethe Christensen—were staying alone in a house while their husbands were out fishing. It was a cold evening in March, and the alleged murderer arrived in a rowboat stolen from the harbor in Portsmouth.
The evidence points to one Louis Wagner, who had worked in the service of the Hontvets, who themselves came from Norway in 1866 (Wagner helped work on Mathew Hontvet’s fishing boat in exchange for room and board).
On the evening of the murder, Karen was sleeping in the kitchen for the night—as she normally lived on a neighboring island where she was employed. It was Karen who was first accosted by the intruder who beat her with a chair in the kitchen. Maren saw this, and tried to save Anethe by hiding her behind a bolted door; however, the murderer broke the door down and killed Anethe with an axe. Maren, unable to help a crippled Karen, escaped by jumping out of a window and hiding behind a rock until the following dawn. The intruder then strangled Karen.

The circumstantial evidence incriminating Wagner was quite complicated; he had been asked by Mathew Hontvet and his family members to help them pick up fishing bait in Portsmouth on the day of the murder, and, when this shipment was delayed, Wagner would therefore have known that the women would be home alone.

Additionally, Karen’s purse with $15 in it was never recovered from the house, and, having returned to Portsmouth the following day (where Wagner lived and had supposedly stolen the rowboat), Wagner reportedly made purchases totaling $15. The household money was not stolen, though Wagner likely knew where it was kept.