A Vancouver Island running store is offering a $1,000 reward for the arrest of a sex assault suspect they say is intimidating female joggers.

A naked man wearing only a gorilla mask rubbed himself against a woman running on a popular Westwood Lake trail near Nanaimo on April 23.

She was able to break free by kicking him, but encountered the man again just a kilometre away on the same trail. Despite efforts to track the suspect using police dogs, he got away, and no one is in custody.

Frontrunners Nanaimo owner Norm Thibault told ctvbc.ca the incident has left female joggers and walkers shaken, with many scared to use their regular route.

"I have a wife and sisters, female staff members and female customers and we found it offensive that they couldn't have the same opportunities to feel safe running outside anymore," he said.

The suspect had been seen masturbating in the bushes earlier that day.

After the attack, Nanaimo RCMP cautioned women to always run with a partner and, if possible, carry a cell phone and whistle.

But Thibault said many of his customers use the popular trails to jog daily and shouldn't have to arm themselves.

"It's not fair that people tell you should always run with someone or not carry an iPod – that's crap. Our society has come to accept that it's risky behavior, but it's not," he said.

The suspect is described as 5-10, 170 pounds with dark hair.

Meanwhile, Nanaimo Mounties issued a public warning Tuesday about a man who rubbed himself against a woman in a local thrift store before masturbating in front of her.

The man left the store and drove away in a black Ford pickup truck.

Const. Gary O'Brien said the cases are not connected, but disturbing nonetheless.

"This is a random and terrible incident for someone to go through," he said.

The suspect is described as a white male in his late thirties with short brown hair.

Anyone with information about either incident is urged to call police or Crime Stoppers.