A British husband on the run after police suspected him of killing his wife and her mother has been tracked down to a California homeless camp, said officials.

Dave McCann, 49, fled on 7 May after investigators said he fatally stabbed his 36-year-old estranged wife, Tierney Cooper-McCann, and her mother, Judith Cooper, 68, in the couple's house in Clovis, California.

He was found sleeping in the woods near a bike trail in the small coastal town of Seaside. Police tracked him based on a tip from a homeless person.

"McCann went off the grid," Clovis police chief Matt Basgall said at a press conference. "There was no technology to be used. There was no cellphones. There was no ATM transactions or anything else to use."

McCann's sister-in-law survived the attack. She told KFSN-TV that he kicked in the door of the home were the three women were staying together, threatening violence.

"I went in and grabbed the phone and was getting ready to call 911 and by the time I walked out he was slitting her throat," Cortney Cooper Rider said of her sister.

"He looked at me and said, 'You're next,' and I immediately ran out the front door and ran to the next-door neighbours."

She said when McCann couldn't get to her, he returned to the house and killed her mother, who had been hiding in a back bedroom. Police later found the mother and daughter dead, lying side by side.

McCann was the CEO of SOS Energy and Property Solutions. A website for the company now says: "Due to circumstances beyond our control, this company is closing. Our prayers are dedicated to the Cooper family."

Relatives said McCann seemed to crack under the strains of a failing marriage and business. Until he was located, remaining family members feared he would return to kill again.

"He has lost his mind and I'm really concerned," Rider said before McCann was captured by police. "Not only for myself and for my family members but I'm really concerned for the community at large."

McCann had run a property development business in the UK before moving to California. His social media pages suggest he had lived in the city of Clovis for about a year.