Police hunting for missing schoolgirl Alice Gross, 14, have arrested a second man on suspicion of murder.
A statement released by Scotland Yard said the 51-year-old man was detained by police in Hanwell around 1.35pm on Sunday (7 September).
A 25-year-old suspect was also arrested in the Ealing area around 5pm on Saturday (6 September). Both men remain in custody at a west London police station.
A Metropolitan Police spokesman said: "All lines of enquiry are still open at this time and this remains a missing person investigation at this stage."
Alice, who suffers from anorexia, disappeared from her home in Hanwell, west London, on Thursday 28, August.
She left her home at around 1pm and was captured on CCTV an hour later on the canal towpath near Brentford Lock, walking towards the River Thames. Her purple rucksack was found on Thursday near the River Brent.
Police divers have carried out a search of a section of the Grand Union Canal in Brentford on Sunday.
Officers with sniffer dogs were also operating on the canal towpath, close to where Alice was last seen 10 days ago.
Earlier, the Met Police released new pictures of cyclists riding past the spot where Alice was last spotted, shortly before her disappearance.
The grainy footage show three cyclists riding along the towpath by the Trumpers Way Canal Bridge in Hanwell, moments before Alice walks past at 4.23pm.
They are followed by two more cyclists who pass under the bridge on the Grand Union Canal.
Detective Chief Inspector Andy Chalmers from the Homicide and Major Crime Command said: "I would urge everyone to take a good look at the pictures ... to see if it jogs any memories of the day Alice went missing."
Alice is described as being 5ft 2in tall, slim, with shoulder-length, light brown hair.
When her family last saw her, she was wearing dark blue jeans, a dark green lacy cardigan and denim Van's shoes. She may also be wearing tartan-framed spectacles.
The CCTV footage, released earlier this week, showed she had taken her cardigan off and was wearing a dark grey T-shirt.
Officers also urged anyone who may have befriended Alice on a song-writing workshop at the Camden Roundhouse to come forward.
A large social media campaign has been under way since the teenager went missing and hundreds of posters have been distributed around the area.
Alice's mother Rosalind Hodgkiss appealed to her daughter directly on the Facebook page Find Alice Gross, saying: "Alice if you can see this, please know sweetheart that all of us love you and miss you desperately.
"My love please get in touch and let someone know you are safe. Alice please come home. Mum."
"We are desperate to know that she is safe and we really want her to know that we want her home, and we are desperate for her to know how loved she is."
Anyone with information can call police on 020 8358 0100, Ealing Missing Persons Unit on 020 8246 1018 or the charity Missing People on 116 000.